Nass River Steelhead Life History Characteristics Pertaining to the Nass Habitat Capability Model

NASS RIVER STEELHEAD LIFE HISTORY CHARACTERISTICS PERTAINING TO THE NASS HABITAT CAPABILITY MODEL

C.K. Parken1

British Columbia Ministry of Environment, Lands and Parks Fisheries Branch Skeena Region PO Box 5000 Smithers, B.C. V0J 2N0

Skeena Fisheries Report SK#110

July, 1997

1 Cascadia Natural Resource Consulting, PO Box 4456, Smithers, B.C., V0J 2N0

Nass River steelhead life history characteristics

Abstract

Information on populations of adult summer (Cranberry River, Damdochax Creek, Kwinageese River, Meziadin River, Nass River fishwheels) and winter (Chambers Creek, Ishkheenickh River, Tseax River) steelhead in the Nass River watershed was gathered from a variety published technical reports and unpublished data from the Skeena Region Ministry of Environment, Lands and Parks files (Smithers). The information was pooled among years (1974-1996) and sampling methods (angling, tangle nets fishwheels etc.) to increase sample sizes and improve inferences on the life history characteristics specific to the Nass habitat capability model. Male and female steelhead were generally similar in body size within tributary populations. Among summer steelhead, Damdochax steelhead were similar in body size to Kwinageese and Meziadin steelhead, however Damdochax steelhead were larger than Cranberry steelhead. Winter steelhead populations were similar in body size, and they were generally larger than summer steelhead populations. The mean length of male summer steelhead ranged from 68.3 cm (Cranberry River) to 78.4 cm (Damdochax Creek), whereas the mean length of male winter steelhead ranged from 73.2 cm (Ishkheenickh River) to 79.7 cm (Tseax River). The mean length of female summer steelhead ranged from 68.7 cm (Cranberry River) to 74.5 cm (Damdochax Creek), whereas the mean length of female winter steelhead ranged from 72.8 cm (Tseax River) to 87.0 cm (Chambers Creek). Mean smolt age ranged from 3.00 years (Meziadin River) to 3.74 years (Damdochax Creek) and steelhead were most frequently freshwater age 3 or 4 in the Nass River watershed. Fecundity estimates ranged from 2597 eggs/fish (Cranberry River) to 4264 eggs/fish (Chambers Creek) and were generally higher for winter than summer steelhead, due to the larger body size of winter steelhead.

Life history characteristics and provincial biostandards were used to estimate the relative productivity of Nass River steelhead populations. Winter steelhead populations were generally more productive than summer steelhead populations due to larger body size. For winter steelhead, Chambers Creek (Beverton-Holt A = 0.80) was the most productive and Tseax River (A = 0.59) was the least productive. Among summer steelhead, the Meziadin River population was the most productive (A = 0.74) and the Cranberry River population was the least productive (A = 0.35). Life history model estimates (i.e. recruits per spawner, allowable harvest rates, Beverton-Holt’s A value) were lower when calculated with updated biostandards than with biostandards used in the Skeena steelhead carrying capacity model.

Monte Carlo simulations indicated the high variability in the updated biostandards increased the probability of populations not meeting sufficient recruitment levels for replacement due to natural (random) variability. The most sensitive life history model parameter was mean smolt age, followed by egg-to-fry

ii Nass River steelhead life history characteristics survival, smolt-to-adult survival and female length, when older biostandards were used (from 1992). However, when the variability of the updated biostandards was incorporated, the most sensitive parameter was smolt-to-adult survival, followed by egg-to-fry survival, mean smolt age and female length. Mean smolt age was probably underestimated for Nass River populations because of limitations in scale aging techniques and the short growing season that probably exists for a number of rearing streams in the Nass River watershed. These negative bias errors in mean smolt age result in overestimates of recruits per spawner, allowable harvest rates and Beverton-Holt’s A value.

iii Nass River steelhead life history characteristics

Table of Contents

Abstract ...... ii Table of Contents...... iv List of Tables...... v List of Figures...... vii List of Appendices...... viii 1.0.0.0 Introduction...... 1 2.0.0.0 Study Area...... 2 3.0.0.0 Methods...... 3 3.1.0.0 Life History Characteristics ...... 3 3.2.0.0 Steelhead Productivity and Allowable Harvest Rates ...... 4 3.3.0.0 Uncertainty and Sensitivity Analysis ...... 6 4.0.0.0 Results ...... 9 4.1.0.0 Life History Characteristics ...... 9 4.1.1.0 Summer Steelhead ...... 9 4.1.1.1 Bell-Irving River ...... 9 4.1.1.2 Cranberry River ...... 9 4.1.1.3 Kiteen River ...... 12 4.1.1.4 Damdochax Creek...... 12 4.1.1.5 Kwinageese River...... 14 4.1.1.6 Meziadin River ...... 15 4.1.1.7 Seaskinnish River...... 17 4.1.1.8 Zolzap Creek and Slough ...... 17 4.1.1.9 Nass River Fishwheels ...... 17 4.1.2.0 Winter Steelhead ...... 21 4.1.2.1 Chambers Creek...... 21 4.1.2.2 Ishkheenickh River ...... 22 4.1.2.3 Tseax River...... 23 4.1.3.0 Summary of Life History Characteristics ...... 25 4.2.0.0 Steelhead Productivity and Allowable Harvest Rates ...... 26 4.2.1.0 Biostandards Used by Tautz et al. (1992) ...... 26 4.2.2.0 Updated Biostandards...... 27 4.3.0.0 Uncertainty and Sensitivity Analysis ...... 28 4.3.1.0 Uncertainty ...... 28 4.3.2.0 Sensitivity ...... 31 5.0.0.0 Discussion ...... 33 5.1.0.0 Life History Characteristics ...... 33 5.2.0.0 Steelhead Productivity and Allowable Harvest Rates ...... 35 5.3.0.0 Uncertainty and Sensitivity Analysis ...... 37 6.0.0.0 Recommendations ...... 39 7.0.0.0 Acknowledgments ...... 40 8.0.0.0 Literature Cited...... 41

iv Nass River steelhead life history characteristics

List of Tables

Table 1. A summary of the mean, standard error, standard deviation and range in fork lengths for male and female summer steelhead in Cranberry, Damdochax, Kwinageese and Meziadin rivers...... 10

Table 3. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Cranberry River summer steelhead...... 12

Table 4. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Damdochax Creek summer steelhead...... 13

Table 5. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Kwinageese River summer steelhead...... 15

Table 6. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Meziadin River summer steelhead...... 16

Table 8. Size, standard error (SE), standard deviation (SD), range and sample size of steelhead sampled at the Nass River fishwheels (1996) at freshwater and ocean age...... 20

Table 9. A summary of the mean, standard error, standard deviation and range in fork lengths for male and female winter steelhead in Chambers Creek, Ishkheenickh River and Tseax River...... 22

Table 10. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Ishkheenickh River winter steelhead...... 23

Table 11. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Tseax River steelhead...... 25

v Nass River steelhead life history characteristics

Table 13. Estimates of summer and winter steelhead population productivity as measured by recruits per spawner (RPS), Beverton-Holt’s A value and allowable harvest rates (µmsy) and calculated from biostandards used by Tautz et al. (1992)...... 26

Table 14. Estimates of summer and winter steelhead population productivity as measured by recruits per spawner (RPS), allowable harvest rates (µmsy) and Beverton-Holt’s A value and calculated from updated Keogh River biostandards. The % change indicates the proportional difference from values calculated with biostandards from Tautz et al. (1992)...... 27

Table 17. The effect of increasing estimates of mean smolt age (MSA) on recruits per spawner (RPS), Beverton-Holt’s A value and allowable harvest rates (µmsy) for Cranberry River steelhead...... 32

vi Nass River steelhead life history characteristics

List of Figures

Figure 1. The Nass River watershed and major tributaries...... 2

Figure 2. Semelparous steelhead life history model used to estimate steelhead productivity and allowable harvest rates by Tautz et al. (1992)...... 5

Figure 3. Percentage of male and female Cranberry River steelhead by 2 cm categories of fork length...... 10

Figure 4. Notched Tukey box plots of summer steelhead length (cm) for Nass River tributaries...... 11

Figure 5. Percentage of male and female Damdochax Creek steelhead by 2 cm categories of fork length...... 13

Figure 6. Percentage of male and female Kwinageese River steelhead by 2 cm categories of fork length...... 14

Figure 7. Percentage of male and female Meziadin River steelhead by 2 cm categories of fork length...... 16

Figure 8. Tukey Box Plots for summer steelhead sampled at the Nass River fishwheels for 1992, 1993, 1994 and 1996...... 19

Figure 9. Percentage of male and female Chambers Creek steelhead by 2 cm categories of fork length...... 21

Figure 10. Percentage of male and female Ishkheenickh River steelhead by 2 cm categories of fork length...... 23

Figure 11. Percentage of male and female Tseax River steelhead by 2 cm categories of fork length...... 24

Figure 12. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for Cranberry River steelhead. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 30

vii Nass River steelhead life history characteristics

List of Appendices

Appendix A. Information on adult steelhead and rainbow trout sampled in Nass River tributaries...... 47

Appendix B. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for Damdochax Creek steelhead. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 56

Appendix C. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for Kwinageese River steelhead. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 57

Appendix D. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for Meziadin River steelhead. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 58

Appendix E. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for steelhead sampled at the Nass River fishwheels in 1996. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 59

Appendix F. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for Chambers Creek steelhead. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 60

Appendix G. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for Ishkheenickh River steelhead. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 61

Appendix H. Probability distributions of recruits per spawner (A), allowable harvest rates (B) and Beverton-Holt’s A value (C) for Tseax River steelhead. The dark shading in A indicates the probabilities of recruitment failure due to random variation...... 62

viii Nass River steelhead life history characteristics

1.0.0.0 Introduction Little information exists on summer and winter steelhead (Oncorhynchus mykiss) in the Nass River watershed (Alexander and Koski 1995; Koski and English 1996). Fisheries research in the Nass River watershed has been hindered by the remoteness, poor access and high glacial turbidity in the mainstem river and tributaries. Several technical reports have examined the run-timing (Link et al. 1993; Link and English 1994, Link 1995), juvenile distribution and stock productivity (Sebastian 1987, Triton 1994a, Triton 1994b, Bustard 1995), and life history characteristics (i.e. Schultze 1981; Lough 1983; Alexander and Koski 1995, Koski and English 1996) of Nass River steelhead. However, additional life history information that has not been summarized existed in report appendixes and in the Ministry of Environment, Lands and Parks (MOELP) Skeena Region data files.

Recent interest and research on Nass River steelhead is directly related to treaty negotiations with the Nisga’a Tribal Council. The Nisga’a are actively involved in subsistence/traditional use fisheries that capture summer and winter steelhead in the mainstem Nass River and tributaries (Bocking and English 1993; Bocking and English 1994a; Bocking and English 1994b; Koski and English 1996). The B.C. Fisheries Branch is currently developing a habitat capability model to estimate conservation goals, allowable harvest rates and surplus steelhead production. The model predictions will aid the Province in the final treaty negotiations process and future fisheries management.

The Nass River habitat capability model relies on life history information, such as female length, fecundity and mean smolt age to predict conservation goals, allowable harvest rates and productivity estimates. These estimates may vary between tributary populations due to a combination of environmental or genetic factors (Waples 1995). Environmental factors, such as growth season length influence juvenile rearing conditions and the duration of stream residence required for steelhead (Bocking and English 1992; Tautz et al. 1992) and Atlantic salmon (Salmo salar; Symons 1979) to grow to smolt size. Similarly, genetic factors or a combination of genetic and environmental factors may influence differences in adult body size (Leider et al. 1986; Bjornn 1987; Hooton et al. 1987; Burgner et al. 1992; Evenson and Ewing 1992) or fecundity (McGregor 1986; DuBois et al. 1989) between steelhead populations. Therefore, the life history characteristics of Nass River steelhead were examined by tributary population. The objectives of this report were: 1) to summarize the available life history data, such as female length, estimated fecundity and mean smolt age by tributary population for the Nass River habitat capability model; 2) to examine the productivity and allowable harvest rates for populations with available empirical data; 3) and to examine the sensitivity of productivity parameters and estimate the uncertainty in predicting allowable harvest rates.

1 Nass River steelhead life history characteristics

2.0.0.0 Study Area

The Nass River originates in the Skeena Mountains of north western British Columbia and flows southwest for approximately 400 km into Portland Inlet (Figure 1). The Nass River watershed is the third largest watershed entirely contained within British Columbia and drains approximately 20 500 km2 (Alexander and Koski 1995). The Nass River has nine main tributaries: Ishkheenickh, Tseax, Tchitin, Cranberry, White, Meziadin, Bell-Irving and Kwinageese rivers and Damdochax Creek. Common fish species in the Nass River watershed include sockeye salmon (O. nerka), chinook salmon (O. tshawytscha), coho salmon (O. kisutch), pink salmon (O. gorbuscha), chum salmon (O. keta), steelhead trout, cutthroat trout (O. clarki), Rocky Mountain whitefish (Prosopium williamsoni), bull char (Salvelinus confluentus), Dolly Varden char (S. malma), largescale sucker (Catostomus macrocheilus), redside shiner (Richardsonius balteatus), peamouth chub (Mylocheilus caurinus) and northern squawfish (Ptychocheilus oregonesis; McPhail and Carveth 1994). In contrast to the nearby Skeena River watershed, lake trout, (S. namaycush), lake whitefish (Coregonus clupeaformis), pygmy whitefish (Prosopium coulteri), lake chub (Couesius plumbeus), longnose dace (Rhinichthys cataractae), white sucker (Catostomus commersoni) and burbot (Lota lota) have not been reported in the Nass River watershed (McPhail and Carveth 1994). The Nass River watershed lies within two ecoprovinces (Coastal Mountains and Sub-Boreal Interior) and contains six biogeoclimatic zones: Alpine Tundra, Sub-Boreal Spruce, Engelmann Spruce-Subalpine Fir, Interior Cedar-Hemlock, Mountain Hemlock, Coastal Western Hemlock (Pojar and Nuzsdorfer 1988). Nass Lake

Bell-Irving River Damdochax Creek Bowser Lake

Meziadin BC Lake Kwinageese River * N White River Nass River Tchitin River 50 km Cranberry River

Canyon City Grease (Gitwinksihlkw) Harbour Kiteen River Town/Community New Seaskinnish River Kincolith River Aiyansh Nass River Fishwheels

Kincolith Tseax River * Meziadin River Fishway Greenville Portland (Lakalzap) Zolzap Creek Inlet Chambers Creek Ishkheenickh River Figure 1. The Nass River watershed and major tributaries.

2 Nass River steelhead life history characteristics

3.0.0.0 Methods

3.1.0.0 Life History Characteristics

A number of sources were investigated to collect data related to the sex, length, freshwater age and ocean age of Nass River steelhead. The data sources included technical reports and unpublished data found in MOELP files, which included data collected by using a variety of methods (angling, tangle nets, fishwheels etc.). Often, partial data were available, such as sex and length but not age, and thus analyses were limited by small samples.

There were suspected discrepancies with one of the data sources. Scale samples collected by LGL Ltd. at the Nass River fishwheels (1992-1994) were suspected to be under-aged and therefore samples were re-aged by the Fisheries Branch office in Smithers (Skeena Region). Scale samples collected during the 1993 telemetry project (Alexander and Koski 1995) and archived at the Fisheries and Oceans Canada scale lab (FOC; Pacific Biological Station, Nanaimo, B.C.) were incomplete or did not correspond with the LGL Ltd. data files (R.C. Bocking, personal communication). However, the mean smolt age of the 1993 telemetry steelhead aged at the FOC scale lab (3.2 years; n=48; Koski and English 1996) was similar to the mean smolt age of the re-aged samples (3.22 years; n=27). Therefore, for steelhead sampled during the 1993 telemetry program, the LGL Ltd. data set was used instead of the re-aged data set because the differences between the mean smolt age were small and the LGL Ltd. data set was complete.

Scale ages were used to estimate life history characteristics, such as mean smolt age, but under-aging errors lead to overestimated life history model estimates (Bocking and English 1992). Scale ages may be biased low (under-aged) by the absence of the first annulus (Hooton et al. 1987) or by the absence of scales being formed during the first year (Jensen and Johnsen 1982; Hooton et al. 1987). From a large sample of Vancouver Island steelhead, evidence for the incomplete scale formation at age 1 was supported by the wide range of circuli counts from the scale focus to the first observed annulus (Hooton et al. 1987). Jensen and Johnsen (1982) reported a range of 10 to 77 percent of Atlantic salmon from a cold (water temperatures exceed 6.50 C for less than 70-80 days) Norwegian river formed scales during their first year. On Vancouver Island, freshwater age 0+ steelhead as large as 46 mm were found devoid of scales (Hooton et al. 1987). In Damdochax Creek (Triton 1994a) and Kwinageese River (Triton 1994b), some yearling steelhead (> 70 mm) had not formed the first annulus and scale ages would be underestimated as 0+. The absence of scale formation in the first year or the first annulus may result in the freshwater ages of some Nass River steelhead being underestimated by one year.

Non-parametric Mann-Whitney U-tests were used to test size (fork length) differences between adult male and female steelhead in tributary populations

3 Nass River steelhead life history characteristics because of the non-normal length distributions (Zar 1984). The lengths of male and female steelhead were compared between rivers using a non-parametric Kruskal- Wallis test because of the non-normal length distributions of male and female steelhead and unequal sample sizes (Zar 1984). If the Kruskal-Wallis test indicated differences in steelhead fork length between rivers, then steelhead lengths were compared graphically using Tukey notched box plots (Chambers et al. 1983; Haas and McPhail 1991). For summer steelhead sampled at the fishwheels, the lengths of males and females were compared between sexes with t-tests and between years with an ANOVA test where Tukey’s HSD test was used for post hoc comparisons (Zar 1984). Parametric tests were used instead of the non-parametric alternatives for fishwheel samples because the samples were approximately normally distributed, in contrast to the tributary samples and did not violate the assumptions of the parametric tests. Mann-Whitney U tests were used to make comparisons between the size of summer steelhead sampled at the fishwheels and summer steelhead sampled in the tributaries (Cranberry, Damdochax, Kwinageese and Meziadin) for males and females.

Fecundity was estimated using the regression developed for Skeena River summer steelhead by Wilkman and Stockerl (1981),

(equation 1) number of eggs/steelhead = 0.5e(2.099*ln(mean length) - 5.156) because a fecundity regression did not exist for either Nass River summer or winter steelhead. The mean smolt ages were compared between tributary populations using an ANOVA test. The mean lengths of steelhead were compared between freshwater and ocean age groups using an ANOVA test and post hoc comparisons were made using Tukey’s HSD test. All statistical comparisons were performed using SPSS computer software (Anonymous 1996).

3.2.0.0 Steelhead Productivity and Allowable Harvest Rates

The relationship between spawner stock size and the number of recruits in the Nass River was assumed to be similar to the Beverton-Holt relationship. Ricker (1975) described the Beverton-Holt relationship as:

(equation 2) R = P/ (1 - A*(1-P/Pr)) where R was the number of recruits, P was the number of spawning adults, A was a measure of stock productivity (Beverton-Holt’s A value) and Pr was the number of spawning adults at replacement (carrying capacity; K). Keogh River winter steelhead had an asymptotic stock-recruitment relationship that resembled the Beverton-Holt stock-recruit curve (Tautz et al. 1992; Ward 1996). Also, Bjornn (1987) reported that the stock-recruitment relationship for Clearwater River summer steelhead (Idaho) followed the Beverton-Holt relationship.

In addition to Beverton-Holt’s A value, steelhead stock productivity was also described as the number of recruits produced per adult spawner when the number

4 Nass River steelhead life history characteristics of adult spawners was at Maximum Sustainable Yield (MSY). Calculation of the number of recruits per spawner and the allowable harvest rate was required to estimate Beverton-Holt’s A value.

The number of recruits per spawner at MSY was calculated using survival rate estimates at each of the life history stages (Figure 2). The number of eggs per steelhead was calculated using the aforementioned fecundity relationship (Wilkman and Stockerl 1981) and mean female length. Tautz et al. (1992) estimated the egg- to-fry survival rate (S1) as 10 percent for Keogh River winter steelhead and applied the estimate to Skeena River summer steelhead. The fry-to-smolt survival rate (S2) was calculated using the relationship described by Tautz et al. (1992) derived from Keogh River winter steelhead and used to estimate the fry-to-smolt survival rate of Skeena River summer steelhead: - 0.7174 * (mean smolt age) (equation 3) S2 = e

Tautz et al. (1992) estimated the smolt-to-adult survival rate (S3) as 14 percent which was the geometric mean of estimates of Keogh River winter steelhead. Egg- to-fry and smolt-to-adult survivals were assumed density independent and smolt-to- adult survival was density dependent for summer and winter steelhead (Bjornn 1987; Tautz et al. 1992). Survival rate estimates based on Keogh River winter steelhead may not accurately reflect survival rates for Nass River summer or winter steelhead because of geographical disparity and differences in life history. However, the Keogh River survival rate estimates were the best available data to model Nass River steelhead.

Number of adults (K) Eggs per fish Female length

Number of eggs deposited Egg to fry survival

S1 Mean Growth Smolt Season Number Age (G7) of fry Fry to smolt Survival survival S 2 Regression

Number of smolts Smolt to adult

survival S3

Number of adults (MSY)

Figure 2. Semelparous steelhead life history model used to estimate steelhead productivity and allowable harvest rates by Tautz et al. (1992).

5 Nass River steelhead life history characteristics

Tautz et al. (1992) estimated the mean smolt age using the growth season length (G7; number of days with water temperature > 7O C), but since G7 data were not available for Nass River tributaries, the mean smolt age was estimated from adult scales. Hooton et al. (1987) and Jensen and Johnsen (1982) discussed some of the negative biases in using adult scales to estimate freshwater ages of steelhead and Atlantic salmon, respectively. However, Bocking and English (1992) illustrated both methods were reasonably similar for B.C. steelhead.

After the survival rate estimates were calculated, the number of recruits per spawner at MSY (RPS) was calculated as:

(equation 4) RPS = 1 * Number of eggs/steelhead * S1 * S2 * S3 The relationship between the number of recruits per spawner and the allowable harvest rate (µmsy) was given by Ricker (1975) as:

(equation 5) µmsy = (RPS - 1) / RPS Given the allowable harvest rate, Beverton-Holt’s A value was calculated using the equation (Ricker 1975): 2 (equation 6) A = 1 - (1 - µmsy) In addition, updated biostandards were used to include the most recent survival estimates and a wider range of environmental variability to make comparisons to the results of the biostandards used by Tautz et al. (1992). The Keogh River egg-to-fry survival was estimated as the geometric mean of data collected from 1976 to 1982 (0.058; Ward and Slaney 1993). Smolt-to-adult survival was estimated as the geometric mean of data collected from 1976 to 1993 (0.104; Ward and Slaney 1988; B. Ward, personal communication). These survival estimates were considerably lower than the estimates used by Tautz et al. (1992) to estimate stock productivity and allowable harvest rates for Skeena River steelhead.

3.3.0.0 Uncertainty and Sensitivity Analysis

The uncertainty in the life history model estimates (i.e. recruits per spawner, allowable harvest rate, Beverton-Holt’s A value) were illustrated by the graphical distribution of the estimate’s variance. The distribution of the life history model estimate’s variance was dependent upon the distribution and amount of variance in the life history parameters (female length, mean smolt age, egg-to-fry survival, smolt-to-adult survival) involved in the estimate’s calculations. Monte Carlo sampling was used to estimate the distribution of a life history model estimate’s variance (Sargent and Wainwright 1996).

With Monte Carlo sampling, the empirical life history model parameters and their distribution were treated as the population and a large number of resamples were randomly drawn with replacement. The resamples were slightly and randomly different from the original life history model parameter and thus were analogous to a

6 Nass River steelhead life history characteristics series of independent random samples. After many resamples, a frequency distribution was constructed of the life history model estimates. The frequency distribution indicated the probability of observing a life history model estimate within a specified range (Sargent and Wainwright 1996).

The statistical distributions of the life history parameters were estimated from the distributions of observed data and from the shape of distributions reported in the literature. The distribution of female lengths for populations with large samples (pooled among years and ocean age groups) did not follow a typical statistical distribution. Therefore, female length was assumed to follow a distribution similar to the observed length frequency histogram for 2 cm categories. Female lengths were pooled over a period from 1974 to 1996 and were influenced by environmental and ocean age variability. However, for populations with small samples (n < 20; Meziadin, Chambers, Ishkheenickh, Tseax) a normal distribution was assumed around the mean female length. Female lengths were not partitioned by ocean age for analyses because of small samples (for some groups) and high inter-annual variability in the proportion of ocean aged steelhead which results from variable recruitment or environmental conditions (Hooton et al 1987; Ward and Slaney 1988; Ward 1989; Ward 1996).

The statistical distribution of fry-to-smolt survival was assumed to be dependent upon the distribution of mean smolt age and the variability resulting from the regression estimation (equation 2). Variability in fry-to-smolt survival was dependent on the additive measurement error (variability in mean smolt age; normally distributed) and multiplicitive variability (regression estimation). Bradford (1995) reported that additive measurement error and multiplicitive variability may cause the statistical distribution of survival rates to be between normal and lognormal distributions. Although fry-to-smolt survivals estimated from the regression developed for Keogh River winter steelhead may not accurately resemble survivals for Nass River winter or summer steelhead, it was the best available estimator for fry-to-smolt survival rates to model Nass River steelhead.

Egg-to-fry survival data (1976-1982; Ward and Slaney 1993) were assumed to follow a lognormal distribution (Bradford 1995). The observed distribution of empirical data were not statistically tested because of low sample size (n=7). The geometric mean and standard deviation of the data were used as the distributional parameters for egg-to-fry survival. Smolt-to-adult survivals were also estimated from Keogh River winter steelhead (1977-1983, Ward and Slaney 1988; 1976-1993, unpublished data, B. Ward, personal communication) and were modeled by a lognormal distribution (Peterman 1981; Bradford 1995). The geometric mean and standard deviation were used as the distributional parameters for smolt-to-adult survival. Although Keogh River winter steelhead smolt-to-adult and egg-to-fry survival rates may not be indicative of the survival estimates for Nass River summer or winter steelhead because of geographical disparity and life history differences, they were the best available data to model Nass River steelhead.

7 Nass River steelhead life history characteristics

The sensitivity of the life history model estimates was dependent upon the life history parameters involved in the calculations (equations 4, 5 and 6). The sensitivity of a parameter indicates the amount of uncertainty in the life history model estimates resulting from the uncertainty in the measurement of the parameter and from the model sensitivity. Model sensitivity was the overall effect of changes in the value of the parameter on the life history model estimate (Sargent and Wainwright 1996). Thus, some parameters may have a higher influence (more sensitive) on the uncertainty in the life history model estimate than other parameters. By using the empirical data for female length, mean smolt age, egg-to- fry and smolt-to-adult survivals, the Monte Carlo simulations estimated the average life history model estimates expected given escapement under the environmental conditions that existed when the data were collected (NRC 1996).

Sensitivity was calculated by computing the rank correlation coefficients between the life history parameters and the life history model estimates during Monte Carlo simulations. Correlation coefficients indicated the degree to which life history parameters and model estimates change together (Sargent and Wainwright 1996). Therefore high correlation coefficients indicated a high contribution to the variance in the life history model estimate. Positive coefficients indicated that increases in life history parameters resulted in increases in life history model estimates. The parameter’s contribution to the variance in the model estimate was calculated by squaring the rank correlation coefficient (Sargent and Wainwright 1996).

8 Nass River steelhead life history characteristics

4.0.0.0 Results

4.1.0.0 Life History Characteristics

4.1.1.0 Summer Steelhead

4.1.1.1 Bell-Irving River

Information on the adult size and migration timing of Bell-Irving River steelhead was limited to a steelhead telemetry project (Alexander and Koski 1995). Alexander and Koski (1995) sampled a single female (76 cm) and a single male (74 cm) at the Nass River fishwheels on July 22 and August 10, 1993, respectively. The estimated fecundity for Bell-Irving steelhead was 3211 eggs/fish (equation 1), based on the length of the 76 cm female. The female was freshwater age 2 and ocean age 2+, but the freshwater age may be negatively biased. Scale age data were not available for the male.

4.1.1.2 Cranberry River

Information and data for adult Cranberry River steelhead was from a steelhead telemetry project (Alexander and Koski 1995), memorandum letters and scale cards in the Skeena Region MOELP Fisheries Branch files (Smithers). At the Nass River fishwheels, Cranberry River steelhead were sampled from July 23 to September 30, 1993 (Alexander and Koski 1995). Steelhead were sampled in the Cranberry River on November 1, 1996, October 20, 1995, October 22, 1980, October 30 to November 28, 1979, September 19 to 21, 1978, September 17, 1977 to April 16, 1978, April 3, 1977, October 30, 1975, and November 7, 1974 (Appendix A). Of the 157 steelhead sampled, 157 had length data, 136 had scale age data and 136 had length and scale age data (Appendix A).

Male (mean = 68.3 cm) and female (mean = 68.7 cm) Cranberry River steelhead were similar in size (Mann-Whitney U = 2975, P = 0.764; Table 1). The length distribution of male and female steelhead illustrated males were similar in size to females (Figure 3). Among ocean age 1+, males (mean = 68.5 cm) were larger than females (mean = 58.1 cm; Mann-Whitney U = 243.5, P = 0.004). However, ocean age 2+ males (mean = 76.4 cm) and females (mean = 74.2 cm) were similar in size (Mann-Whitney U = 476, P = 0.212). The fork lengths of male summer steelhead differed between populations (Kruskal-Wallis = 10.458, P = 0.015; Table 1) and the fork lengths of female summer steelhead differed between populations (Kruskal-Wallis = 8.206, P = 0.042; Table 1). The Kruskal-Wallis results for male and female summer steelhead indicated at least one of the populations (and not necessarily all the populations) was different from another population.

9 Nass River steelhead life history characteristics

Table 1. A summary of the mean, standard error, standard deviation and range in fork lengths for male and female summer steelhead in Cranberry, Damdochax, Kwinageese and Meziadin rivers. Summer Steelhead Population Kruskal-Wallis Cranberry Damdochax Kwinageese Meziadin P values Female Mean fork length(cm) 68.7 74.5 72.5 71.4 0.042 Standard error (cm) 1.11 1.05 1.64 2.39 Standard deviation (cm) 9.37 5.97 9.00 7.56 Size range (cm) 53-89 61-86 53-89 62-82 Sample size 72 33 30 10 Male Mean fork length(cm) 68.3 78.4 70.0 69.7 0.015 Standard error (cm) 1.04 2.67 1.96 4.93 Standard deviation (cm) 9.59 12.50 12.39 12.08 Size range (cm) 52-88 53-99 51-97 58-89 Sample size 85 22 40 6 Mann-Whitney U P values 0.764 0.055 0.421 0.515

30% Females (n=72)

25% Males ( n=85)

20%

15%

10%

5% Percentage of Steelhead 0% 50 54 58 62 66 70 74 78 82 86 90 94 96 Fork Length (cm)

Figure 3. Percentage of male and female Cranberry River steelhead by 2 cm categories of fork length.

The length distributions of Nass River summer steelhead were visually compared between rivers with notched Tukey box plots (Figure 4). Male and female steelhead were pooled to increase sample sizes for comparisons, since the fork lengths were similar between male and female summer steelhead (Table 1). Damdochax steelhead were similar in size to Kwinageese and Meziadin steelhead, however, Damdochax steelhead were larger than Cranberry steelhead (Figure 4).

10 Nass River steelhead life history characteristics

n=55 n=70 n=157 n=16 Fork Length (cm)

Cranberry Damdochax Kwinageese Meziadin River Creek River River

Nass River Tributary Figure 4. Notched Tukey box plots of summer steelhead length (cm) for Nass River tributaries. The extent of the box represented the 25th and 75th percentiles, the lines (whiskers) extending from the boxes represent the data range and the asterisks (*) represent statistical outliers. Nonoverlapping notches between each river indicate a statistical difference at a rough 5% significance level (Chambers et al. 1983; Haas and McPhail 1991).

The estimated fecundity of Cranberry River steelhead was 2597 eggs/fish (equation 1). Five percent of Cranberry River steelhead were repeat spawners (4 females and 3 males) and four percent had regenerated scales during the freshwater growth period. The mean smolt age was 3.53 years, with 48, 51 and 1 percent of steelhead being freshwater age 3, 4 and 5, respectively (Table 2). The mean smolt age of Cranberry River steelhead differed from Meziadin River steelhead (ANOVA, F = 4.34, P = 0.001; Tukey HSD = 0.53, P = 0.002), but was similar to the mean smolt age of Damdochax Creek and Ishkheenickh, Kwinageese and Tseax river steelhead (Tukey HSD, P > 0.05; Table 2). Freshwater age 3 adult steelhead were similar in size to freshwater age 4 adult steelhead (t-test = 0.474, P = 0.636; Table 3). Forty-five (45), 50, 3 and 2 percent of Cranberry River steelhead were ocean age 1+, 2+, 3+ and 4+, respectively. Ocean age 1+ steelhead were significantly smaller than ocean age 2+ steelhead (t-test = 17.339, P <0.0005; Table 3). Ocean ages 3+ and 4+ were excluded from the analysis because of small samples (Table 3).

Table 2. A summary of the mean, standard error, standard deviation and range in smolt age for steelhead in the Cranberry (Cran.), Damdochax (Damd.), Ishkheenickh (Ishk.), Kwinageese (Kwin.), Meziadin (Mez.) and Tseax rivers. Steelhead Population ANOVA Cran. Damd. Ishk. Kwin. Mez. Tseax P values Mean smolt age (yrs) 3.53 3.74 3.44 3.53 3.00 3.38 0.001 Standard error (yrs) 0.05 0.11 0.12 0.07 0.16 0.13 Standard deviation (yrs) 0.52 0.59 0.51 0.50 0.63 0.50 Age range (yrs) 3-5 2-5 3-4 3-4 2-4 3-4 Sample size 131 27 18 57 16 16

11 Nass River steelhead life history characteristics

Table 3. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Cranberry River summer steelhead. Freshwater Age Ocean Age 3 4 5 1+ 2+ 3+ 4+ Mean length (cm) 68.8 68.0 66.0 59.6 75.1 74.2 84.7 Standard error (cm) 1.15 1.23 NA 0.51 0.73 1.71 1.70 Standard deviation (cm) 9.16 10.10 NA 4.01 6.05 3.41 2.94 Length range (cm) 53-88 53-89 NA 53-74 63-89 71-79 81-86 Sample size 63 67 1 61 68 4 3

4.1.1.3 Kiteen River

The Kiteen River is a major tributary to the Cranberry River (Figure 1; Sebastian 1987). Information on the adult size and age of Kiteen River steelhead was from scale cards in the Skeena Region MOELP Fisheries Branch files (Smithers). Steelhead were sampled on December 2, 1984, August 24, 1982 and on April 3, 1977. Two of the three steelhead sampled were female. The male steelhead was 81 cm, but female lengths were not recorded. Scale ages were available for two steelhead, both freshwater age 3 and ocean age 2+. Kiteen River steelhead may be similar to Cranberry steelhead because of the proximity of the two streams, however comparisons were limited by small samples.

4.1.1.4 Damdochax Creek

Information on adult steelhead in the Damdochax Creek was from a steelhead telemetry project (Alexander and Koski 1995), memorandum letters and scale cards in the Skeena Region MOELP Fisheries Branch files (Smithers). One Damdochax Creek steelhead was captured at the Nass River fishwheels on July 26, 1993 (Alexander and Koski 1995). Steelhead were sampled in the Damdochax Creek from September 6 to October 28, 1996, on May 4, 1994, May 1979 and from October 1 to December 7, 1979 (Appendix A). Of the 74 steelhead sampled, 55 had length data, 31 had scale age data and 12 had length and scale age data (Appendix A).

Male (mean = 78.4 cm) and female (mean = 74.5 cm) Damdochax Creek steelhead were similar in size (Mann-Whitney U = 251.5, P = 0.055; Table 1). The length distribution of male and female steelhead illustrated that males were slightly larger than females (Figure 5). Statistical comparisons were not made between sexes within ocean age groups because of small samples. The fork lengths of male summer steelhead differed between populations (Kruskal-Wallis = 10.458, P = 0.015; Table 1) and the fork lengths of female summer steelhead differed between populations (Kruskal-Wallis = 8.206, P = 0.042; Table 1). The Kruskal-Wallis results for male and female summer steelhead indicated at least one of the populations (and not necessarily all the populations) was different from another population. Damdochax steelhead were similar in size to Kwinageese and Meziadin steelhead, however Damdochax steelhead were larger than Cranberry steelhead (Figure 4).

12 Nass River steelhead life history characteristics

30% Females (n=33)

25% Males ( n=22)

20%

15%

10%

5% Percentage of Steelhead 0% 50 54 58 62 66 70 74 78 82 86 90 94 96 Fork Length (cm)

Figure 5. Percentage of male and female Damdochax Creek steelhead by 2 cm categories of fork length.

The estimated fecundity of Damdochax Creek steelhead was 3079 eggs/fish (equation 1). Thirteen (13) percent of Damdochax Creek steelhead were repeat spawners (3 females and 1 male) and 13 percent had regenerated scales during the freshwater growth period. The mean smolt age was 3.74 years, with 4, 22, 70 and 4 percent of steelhead being freshwater age 2, 3, 4 and 5, respectively (Table 2). The mean smolt age of Damdochax Creek steelhead differed from Meziadin River steelhead (ANOVA, F = 4.34, P = 0.001; Tukey HSD = 0.74, P < 0.0005), but was similar to the mean smolt age of Cranberry, Ishkheenickh, Kwinageese and Tseax river steelhead (Tukey HSD, P > 0.05; Table 2). The mean length of adult steelhead was similar between freshwater age 3 and 4, although the samples were small (t-test = 1.505, P = 0.183; Table 4). Ten (10), 74, 10 and 6 percent of Damdochax Creek steelhead were ocean age 1+, 2+, 3+ and 4+, respectively. The mean length of adult steelhead at different ocean ages was not tested because of small samples for ocean age 1+, 3+ and 4+ (Table 4).

Table 4. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Damdochax Creek summer steelhead. Freshwater Age Ocean Age 2 3 4 1+ 2+ 3+ 4+ Mean length (cm) 67.0 83.8 73.2 61 73.8 94 85 Standard error (cm) NA 6.73 3.82 NA 1.81 NA 1.30 Standard deviation (cm) NA 11.66 8.54 NA 5.12 NA 1.84 Length range (cm) NA 71-94 61-85 NA 67-85 NA 84-86 Sample size 1 3 5 1 8 1 2

13 Nass River steelhead life history characteristics

4.1.1.5 Kwinageese River

Information on adult steelhead in the Kwinageese River was from a steelhead telemetry project (Alexander and Koski 1995), a technical report (Schultze 1981), memorandum letters and scale cards in the Skeena Region MOELP Fisheries Branch files (Smithers). One Kwinageese River steelhead was sampled at the Nass River fishwheels on August 9, 1993 (Alexander and Koski 1995). Steelhead were sampled in the Kwinageese River on October 19, 1995, October 12 to 13, 1982, and October 16 to 18, 1981 (Appendix A). Of the 70 steelhead sampled, 70 had length data, 59 had scale age data and 59 had length and scale age data (Appendix A).

Male (mean = 70.0 cm) and female (mean = 72.5 cm) Kwinageese River steelhead were similar in size (Mann-Whitney U = 532.5, P = 0.421; Table 1). The length distribution of male and female steelhead illustrated males were similar in size to females (Figure 6). Ocean age 1+ males and females were similar in size (Mann-Whitney U = 29.5, P = 0.138). Among ocean age 2+ steelhead, males (mean = 82.4 cm) were larger than females (mean = 72.8 cm; Mann-Whitney U = 19.5, P < 0.0005). The fork lengths of male summer steelhead differed between populations (Kruskal-Wallis = 10.458, P = 0.015; Table 1) and the fork lengths of female summer steelhead differed between populations (Kruskal-Wallis = 8.206, P = 0.042; Table 1). The Kruskal-Wallis results for male and female summer steelhead indicated at least one of the populations (and not necessarily all the populations) was different from another population, although Kwinageese steelhead were similar in size to Cranberry, Damdochax and Meziadin steelhead (Figure 4).

30% Females (n=30)

25% Males ( n=40)

20%

15%

10%

5% Percentage of Steelhead 0% 50 54 58 62 66 70 74 78 82 86 90 94 96 Fork Length (cm)

Figure 6. Percentage of male and female Kwinageese River steelhead by 2 cm categories of fork length.

The estimated fecundity of Kwinageese River steelhead was 2908 eggs/fish (equation 1). Five percent of Kwinageese River steelhead were repeat spawners (1 female and 2 males) and four percent had regenerated scales during the freshwater growth period. The mean smolt age was 3.53 years, with 47 and 53 percent of steelhead being freshwater age 3 and 4, respectively (Table 2). The mean smolt age of Kwinageese River steelhead differed from Meziadin River steelhead

14 Nass River steelhead life history characteristics

(ANOVA, F = 4.34, P = 0.001; Tukey HSD = 0.53, P = 0.006), but was similar to the mean smolt age of Damdochax Creek and Cranberry, Ishkheenickh and Tseax river steelhead (Tukey HSD, P > 0.05; Table 2). Adult Kwinageese River steelhead with freshwater age 4 (mean = 72.4 cm) were larger than steelhead with freshwater age 3 (mean = 65.7 cm; t-test = 2.440, P = 0.018; Table 5). Forty-four (44), 48 and 8 percent of Kwinageese River steelhead were ocean age 1+, 2+ and 3+, respectively. The mean length of adult steelhead was significantly different between ocean ages (ANOVA, F = 73.77, P < 0.0005) and post hoc tests (Tukey HSD) indicated the mean length of adults increased with ocean age (P < 0.0005; Table 5).

Table 5. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Kwinageese River summer steelhead. Freshwater Age Ocean Age 3 4 1+ 2+ 3+ Mean length (cm) 65.7 72.4 59.9 75.8 87.9 Standard error (cm) 2.10 1.80 1.03 1.15 3.65 Standard deviation (cm) 10.89 9.85 5.25 6.09 8.15 Length range (cm) 51-94 56-97 51-76 61-89 76-97 Sample size 27 30 26 28 5

4.1.1.6 Meziadin River

Information on adult steelhead size and age in the Meziadin River was from the Meziadin River fishway (unpublished data; M.R. Link, personal communication; Figure 1), DNA tissue sampling in 1996 and a steelhead telemetry project (Alexander and Koski 1995). Steelhead were sampled at the Meziadin River fishway from September 17 to 22, 1996. From October 9 to 22, 1996, nine steelhead were sampled in the Meziadin River downstream of Meziadin Lake. Meziadin River steelhead were sampled at the Nass River fishwheels on August 3 and 5, 1993 (Alexander and Koski 1995). Length and scale age data were available for all 16 steelhead sampled (Appendix A).

Male (mean = 69.7 cm) and female (mean = 71.4 cm) Meziadin River steelhead were similar in size (Mann-Whitney U = 24, P = 0.515; Table 1). The length distribution of male and female steelhead illustrated that males were similar in size to females (Figure 7). Statistical comparisons were not made between sexes within ocean age groups because of small samples. The fork lengths of male summer steelhead differed between rivers (Kruskal-Wallis = 10.458, P = 0.015; Table 1) and the fork lengths of female summer steelhead differed between populations (Kruskal-Wallis = 8.206, P = 0.042; Table 1). The Kruskal-Wallis results for male and female summer steelhead indicated at least one of the populations (and not necessarily all the populations) was different from another population, although Meziadin steelhead were similar in size to Cranberry, Damdochax and Kwinageese steelhead (Figure 4).

15 Nass River steelhead life history characteristics

40% Females (n=10) 35% Males ( n=6) 30% 25% 20% 15% 10% 5% Percentage of Steelhead 0% 50 54 58 62 66 70 74 78 82 86 90 94 96 Fork Length (cm)

Figure 7. Percentage of male and female Meziadin River steelhead by 2 cm categories of fork length.

The estimated fecundity of Meziadin River steelhead was 2816 eggs/fish (equation 1). Six percent of Meziadin River steelhead were repeat spawners (1 male) and none of the 16 steelhead had regenerated scales. The mean smolt age was 3.00 years, with 19, 62 and 19 percent of steelhead being freshwater age 2, 3 and 4, respectively (Table 2). The mean smolt age of Meziadin River steelhead differed from Cranberry, Damdochax and Kwinageese river steelhead (ANOVA, F = 4.34, P = 0.001; Tukey HSD = 0.53, P = 0.002, Tukey HSD = 0.74, P < 0.0005, and Tukey HSD = 0.53, P = 0.006, respectively), but was similar to the mean smolt age of Ishkheenickh and Tseax river steelhead (Tukey HSD = 0.44, P = 0.140, and Tukey HSD = 0.38, P = 0.337, respectively; Table 2). The mean length of adult steelhead was similar between freshwater age 2, 3 and 4 (ANOVA, F = 0.904, P = 0.429; Table 6). Fifty (50), 44 and 6 percent of Meziadin River steelhead were ocean age 1+, 2+ and 3+, respectively. Ocean age 2+ steelhead were significantly larger than ocean age 1+ steelhead (t-test = 7.514, P < 0.0005; Table 6).

Table 6. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Meziadin River summer steelhead. Freshwater Age Ocean Age 2 3 4 1+ 2+ 4+ Mean length (cm) 75.7 68.4 73.7 63 77 89 Standard error (cm) 6.44 3.05 1.76 0.85 1.75 NA Standard deviation (cm) 11.15 9.63 3.06 2.41 4.65 NA Length range (cm) 63-84 58-89 71-77 58-66 71-84 NA Sample size 3 10 3 8 7 1

16 Nass River steelhead life history characteristics

4.1.1.7 Seaskinnish River

Information on the adult size and migration timing of Seaskinnish River steelhead was limited to a steelhead telemetry project (Alexander and Koski 1995). Alexander and Koski (1995) sampled one male (75 cm) at the Nass River fishwheel on August 28, 1993. The steelhead had regenerated the freshwater growth portion of the scale, but was ocean age 2+.

4.1.1.8 Zolzap Creek and Slough

Information on the adult size and migration timing of Zolzap Creek steelhead was limited to a steelhead telemetry project (Alexander and Koski 1995). Alexander and Koski (1995) sampled one female (77 cm) at the Nass River fishwheels on August 16, 1993. The estimated fecundity for Zolzap Creek steelhead was 3300 eggs/fish (equation 1), based on the length of the 77 cm female. The steelhead was freshwater age 4 and ocean age 3+, but the freshwater age may be negatively biased.

4.1.1.9 Nass River Fishwheels

Information on steelhead captured at the Nass River fishwheels was obtained from Koski and English (1996) and from LGL Ltd. files (R.C. Bocking, personal communication). From 1992 to 1996, steelhead were sampled at the fishwheels from late June to early September (Link et al. 1993; Link and English 1994; Koski and English 1996). Length and sex data were from LGL Ltd. files (R.C. Bocking, personal communication; n=18, 78, 111 and 416 for 1992, 1993, 1994 and 1996, respectively) whereas age data were from Koski and English (1996; n=16, 48 and 4 for 1992, 1993 and 1994, respectively) and Skeena Region MOELP data files (n=382 for 1996).

From 1992 to 1994, male and female steelhead were similar in size (t-test P > 0.05; Table 7), but differed in size for 1996 (t-test = 2.247, P = 0.025). Male steelhead were similar in size between years (ANOVA, F = 1.74, P = 0.159; Table 7). Female steelhead differed in size between years (ANOVA, F = 3.945, P = 0.009), and post hoc tests indicated 1993 females differed from those in 1992 (Tukey HSD = 7.82, P = 0.011) and 1996 (Tukey HSD = 3.68, P = 0.034), but all other years were similar (Tukey HSD, P > 0.05). The Tukey box plot indicated steelhead (pooled males and females) sampled at the fishwheels were graphically similar in size between 1992, 1993, 1994 and 1996 (Figure 8). When pooled among years, male steelhead sampled at the fishwheels (mean = 70.4 cm) were similar in size to pooled male steelhead sampled in the tributaries (Cranberry, Damdochax, Kwinageese and Meziadin; mean = 70.3 cm; Mann-Whitney U = 24167, P = 0.549). However, female steelhead sampled at the fishwheels (mean = 69.2 cm) differed in size to pooled female steelhead sampled in the tributaries (mean = 70.9 cm; Mann-Whitney U = 19663, P = 0.049), although the magnitude of differences was small.

17 Nass River steelhead life history characteristics

Table 7. A summary of the mean, standard error, standard deviation and range in fork lengths male and female summer steelhead sampled at the Nass River fishwheels in 1992, 1993, 1994 and 1996. 1992 1993 1994 1996 ANOVA P values Female Mean fork length(cm) 64.6 72.5 69.1 68.8 0.009 Standard error (cm) 1.98 1.51 1.03 0.55 Standard deviation (cm) 7.40 10.14 8.18 7.87 Size range (cm) 52-73 51-97 48-88 50-89 Sample size 14 45 63 207 Male Mean fork length(cm) 61.3 68.1 70.1 70.8 0.159 Standard error (cm) 4.49 1.63 1.48 0.70 Standard deviation (cm) 9.18 8.92 10.12 10.07 Size range (cm) 52-71 48-80 54-91 48-97 Sample size 4 30 47 209 t-test P values 0.452 0.061 0.562 0.0251 1. T-test p-value for equal variances not assumed. The t-test is robust to deviations from the assumption of equal variance when samples sizes are approximately equal (Zar 1984).

The estimated fecundity of steelhead sampled at the fishwheels in 1996 was 2605 eggs/fish (equation 1). In 1996, 14 of the 382 steelhead sampled (4%; 8 males, 5 females and 1 unknown) were repeat spawners and 58 (15%) had regenerated scales. Scale samples collected at the fishwheels from 1992 to 1994 were re-aged by the Fisheries Branch office in Smithers (Skeena Region) because the samples aged by the DFO scale lab were suspected to be under-aged. However, not all the samples were available at the DFO scale lab and therefore the sample sizes differed from the results reported in Table 4 of Koski and English (1996). The mean smolt ages of steelhead sampled at the fishwheels and re-aged were 3.29 years (standard error = 0.13) for 1992 (n=14), 3.22 years (standard error = 0.08) for 1993 (n=27), and 3.23 years (standard error = 0.05) for 1994 (n=73). Koski and English (1996) reported the mean smolt age of steelhead was 2.8 in 1992 (n=16), 3.2 in 1993 (n=48) and 3.8 years in 1994 (n=4). In 1996, the mean smolt age was 3.27 years (n=325; standard error = 0.025, standard deviation = 0.46) and 0.3, 72.6, 26.8 and 0.3 percent of steelhead were freshwater age 2, 3, 4 and 5, respectively.

18 Nass River steelhead life history characteristics

n=110 n=412 n=75

n=18 Length (cm)

1992 1993 1994 1996

Year

Figure 8. Tukey Box Plots for summer steelhead sampled at the Nass River fishwheels for 1992, 1993, 1994 and 1996. The extent of the box represented the 25th and 75th percentiles, the lines (whiskers) extending from the boxes represent the data range and the asterisks (*) represent statistical outliers.

In 1996, male and female steelhead were similar in size at ocean age 1+, 3+ and 4+ (Mann-Whitney U = 1195, P = 0.84, Mann-Whitney U = 23.5, P = 0.27, Mann-Whitney U = 8.5, P = 0.73, respectively), but males (mean = 74.3 cm) were larger than females (mean = 72.1 cm) at ocean age 2+ (Mann-Whitney U = 6154, P < 0.0005; Table 8). Among males, length increased with ocean age (ANOVA, F = 115.90, P < 0.0005; Tukey HSD, P < 0.025), but was similar between ocean age 3+ and 4+ (Tukey HSD = 0.61, P = 0.997; Table 8). Adult male steelhead were similar in size between freshwater age 3 and 4 (t-test = 1.45, P = 0.151). Among females, length increased with ocean age (ANOVA, F = 76.96, P < 0.0005; Tukey HSD, P < 0.025), but was similar between ocean age 3+ and 4+ (Tukey HSD = 0.01, P = 0.999). Adult female steelhead were similar in size between freshwater age 3 and 4 (t-test = 0.52, P = 0.604). Statistical comparisons of lengths were not performed on freshwater and ocean age steelhead collected from 1992 to 1994 because the age data (Table 4 in Koski and English 1996) were not linked to the length data in the LGL Ltd. files.

19 Nass River steelhead life history characteristics

Table 8. Size, standard error (SE), standard deviation (SD), range and sample size of steelhead sampled at the Nass River fishwheels (1996) at freshwater and ocean age. Freshwater Ocean Age Age Sex 1+ 2+ 3+ 4+ All 2 Female Length (cm) NA 65.0 NA NA 65.0 Sample size NA 1 NA NA 1 3 Female Length (cm) 58.3 72.0 74.25 84.0 69.0 SE (cm) 0.92 0.47 2.10 1.0 0.69 SD (cm) 5.06 4.46 4.19 1.41 7.70 Range (cm) 50-69 56-82 70-80 83-85 50-85 Sample size 30 89 4 2 125 Male Length (cm) 59.3 74.1 82.2 86.0 70.8 SE (cm) 1.06 0.64 4.52 5.00 0.88 SD (cm) 5.70 5.54 10.10 7.07 9.23 Range (cm) 48-71 57-85 74-96 81-91 48-96 Sample size 29 75 5 2 111 4 Female Length (cm) 61.7 73.1 80.0 NA 69.7 SE (cm) 1.00 0.76 0.00 NA 1.05 SD (cm) 3.73 3.96 0.00 NA 6.90 Range (cm) 57-69 64-78 80-80 NA 57-80 Sample size 14 27 2 NA 43 Male Length (cm) 61.8 73.4 78.3 80.5 73.1 SE (cm) 1.97 1.03 8.86 4.50 1.25 SD (cm) 3.95 5.81 17.73 6.36 8.18 Range (cm) 57-65 61-91 59-97 76-85 57-97 Sample size 4 32 4 2 43 5 Female Length (cm) NA 67 NA NA 67 Sample size NA 1 NA NA 1 All Female Length (cm) 58.7 72.1 77.1 77.8 NA SE (cm) 0.70 0.38 1.81 4.27 NA (includes SD (cm) 4.97 4.32 4.78 8.54 NA steelhead Range (cm) 50-69 56-82 70-83 66-85 NA with Sample size 51 127 7 4 NA regenerated Male Length (cm) 59.3 74.3 81.3 83.3 NA scales) SE (cm) 0.82 0.54 3.62 3.17 NA SD (cm) 5.65 6.18 11.99 6.34 NA Range (cm) 48-78 49-92 59-97 76-91 NA Sample size 48 130 10 4 NA

20 Nass River steelhead life history characteristics

4.1.2.0 Winter Steelhead

4.1.2.1 Chambers Creek

Information on adult steelhead size in Chambers Creek was limited to a single study by Bustard (1995). From May 8 to 9, 1994, Bustard (1995) sampled eight male and four female winter steelhead in Chambers Creek. Length data were available for the 12 steelhead, but scale age data were not collected (Appendix A). The skewed sex ratio (one female: three males) was hypothesized to indicate spawning was in progress at this time and that some of the females had emigrated from Chambers Creek (Bustard 1995).

Male (mean = 79.1 cm) and female (mean = 87.0 cm) Chambers Creek steelhead were similar in size (Mann-Whitney U = 8, P = 0.171; Table 9). The length distribution of male and female steelhead illustrated that females were generally larger than males (Figure 9). The fork lengths of male winter steelhead were similar between populations (Kruskal-Wallis = 2.453, P = 0.293; Table 9) and the fork lengths of female winter steelhead were similar between populations (Kruskal-Wallis = 5.160, P = 0.076; Table 9).

Females (n=4) 30% Males ( n=8) 25%

20%

15%

10%

5% Percentage of Steelhead 0% 50 54 58 62 66 70 74 78 82 86 90 94 96 Fork Length (cm)

Figure 9. Percentage of male and female Chambers Creek steelhead by 2 cm categories of fork length.

The estimated fecundity of Chambers Creek steelhead was 4264 eggs/fish (equation 1). The mean smolt age and mean lengths at different ocean ages were not examined due to the absence of scale age data.

21 Nass River steelhead life history characteristics

Table 9. A summary of the mean, standard error, standard deviation and range in fork lengths for male and female winter steelhead in Chambers Creek, Ishkheenickh River and Tseax River. Winter Steelhead Population Kruskal-Wallis Chambers Ishkheenickh Tseax1 P values Female Mean fork length(cm) 87.0 80.2 72.8 0.076 Standard error (cm) 2.74 1.93 4.86 Standard deviation (cm) 5.48 8.21 9.71 Size range (cm) 81-93 64-88 62-83 Sample size 4 18 4 Male Mean fork length(cm) 79.1 73.2 79.7 0.293 Standard error (cm) 3.76 3.59 3.58 Standard deviation (cm) 10.6 9.48 10.75 Size range (cm) 59-92 66-91 63-94 Sample size 8 7 9 Mann-Whitney U P values 0.171 0.101 0.246 1. Tseax River steelhead consisted of winter and summer steelhead

4.1.2.2 Ishkheenickh River

Information on Ishkheenickh River steelhead was from memorandum letters and from scale cards in the Skeena Region MOELP Fisheries Branch files (Smithers). Steelhead were sampled on April 20, 1994, May 7, 1990, April 15 and May 22, 1987, May 5 1985, April 25, 1982, and on May 6 and 13, 1978 (Appendix A). Of the 48 steelhead sampled, 25 had length data, 21 had scale age data, but only 4 had length and scale age data (Appendix A).

Male (mean = 73.2 cm) and female (mean = 80.2 cm) Ishkheenickh River steelhead were similar in size (Mann-Whitney U = 36, P = 0.101; Table 9). The length distribution of male and female steelhead illustrated males were similar in size to females (Figure 10). Statistical comparisons were not made between sexes within ocean age groups because of small samples. The fork lengths of male winter steelhead differed between populations (Kruskal-Wallis = 2.453, P = 0.293; Table 9) and the fork lengths of female winter steelhead differed between populations (Kruskal-Wallis = 5.160, P = 0.076; Table 9).

22 Nass River steelhead life history characteristics

Females (n=18) 30% Males ( n=7) 25%

20%

15%

10%

5% Percentage of Steelhead 0% 50 54 58 62 66 70 74 78 82 86 90 94 96 Fork Length (cm)

Figure 10. Percentage of male and female Ishkheenickh River steelhead by 2 cm categories of fork length.

The estimated fecundity of Ishkheenickh River steelhead was 3594 eggs/fish (equation 1). Twenty-three (23) percent of Ishkheenickh River steelhead were single repeat spawners (3 females, 1 male and 1 unknown sex), 5 percent were double repeat spawners (unknown sex) and 16 percent had regenerated scales during the freshwater growth period. The mean smolt age was 3.44 years, with 56 and 44 percent of steelhead being freshwater age 3 and 4, respectively (Table 2). The mean smolt age of Ishkheenickh River steelhead was similar to mean smolt ages of steelhead from the Cranberry, Damdochax, Kwinageese, Meziadin or Tseax rivers (Tukey HSD, P > 0.05; Table 2). Twenty-four (24), 66, 5 and 5 percent of Ishkheenickh River steelhead were ocean age 1, 2, 3 and 4, respectively. Statistical comparisons of lengths were not performed on freshwater and ocean age steelhead because of small samples (n=4; Table 10).

Table 10. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Ishkheenickh River winter steelhead. Freshwater Age Ocean Age 3 4 2 3 Mean length (cm) 74.9 68.1 68.1 74.9 Standard error (cm) 8.9 0.85 0.85 8.9 Standard deviation (cm) 12.6 1.2 1.2 12.6 Length range (cm) 66-84 67-69 67-69 66-84 Sample size 2 2 2 2

4.1.2.3 Tseax River

Summer and winter steelhead occur sympatrically in the Tseax River. However, only 3 of 16 steelhead were identified as summer steelhead, thus the summer steelhead were pooled with the winter steelhead for analyses. Information on adult steelhead in the Tseax River was from a steelhead telemetry project (Alexander and Koski 1995), memorandum letters and scale cards in the Skeena Region MOELP Fisheries Branch files (Smithers). At the Nass River fishwheels,

23 Nass River steelhead life history characteristics

Tseax River summer steelhead were sampled on August 13 and 14, 1993 (Alexander and Koski 1995). Steelhead were sampled in the Tseax River on April 16, 1987, April 30 1978 and on June 1, 1975 (Appendix A). Of the 17 steelhead sampled, 13 had length data, 17 had scale age data, but only 5 had corresponding length and scale age data (Appendix A) because scale data were not linked to sex and length data.

Male (mean = 79.7 cm) and female (mean = 72.8 cm) Tseax River steelhead were similar in size (Mann-Whitney U = 10.5, P = 0.246; Table 8). The length distribution of male and female steelhead illustrated males were similar in size to females (Figure 11). Statistical comparisons were not made between sexes within ocean age groups because of small samples. The fork lengths of male winter steelhead were similar between populations (Kruskal-Wallis = 2.453, P = 0.293; Table 9) and the fork lengths of female winter steelhead were similar between populations (Kruskal-Wallis = 5.160, P = 0.076; Table 9).

35% Females (n=4) 30% Males ( n=9) 25%

20% 15%

10% 5% Percentage of Steelhead 0% 50 54 58 62 66 70 74 78 82 86 90 94 96 Fork Length (cm)

Figure 11. Percentage of male and female Tseax River steelhead by 2 cm categories of fork length.

The estimated fecundity of Tseax River steelhead was 2933 eggs/fish (equation 1). Twelve (12) percent of Tseax River steelhead were repeat spawners (1 male and 1 unknown sex) and 12 percent had regenerated scales during the freshwater growth period. The mean smolt age was 3.40 years, with 62 and 38 percent of steelhead being freshwater age 3 and 4, respectively (Table 2). The mean smolt age of Tseax River steelhead was similar to the mean smolt ages of steelhead from Damdochax Creek and the Cranberry, Ishkheenickh, Kwinageese or Meziadin rivers (Tukey HSD, P > 0.05; Table 2). Forty-seven (47), 41 and 12 percent of Tseax River steelhead were ocean age 1, 2 and 3, respectively. Statistical comparisons of lengths were not performed on freshwater and ocean age steelhead because of small samples (n=4; Table 11).

24 Nass River steelhead life history characteristics

Table 11. A summary of the mean, standard error, standard deviation and range in adult fork lengths by freshwater and ocean age for Tseax River steelhead. Freshwater Age Ocean Age 3 4 2 3 Mean length (cm) 62.5 77.0 72.4 62 Standard error (cm) 0.71 3.38 3.48 NA Standard deviation (cm) 0.50 5.86 7.77 NA Length range (cm) 62-63 74-84 63-84 NA Sample size 2 3 5 1

4.1.3.0 Summary of Life History Characteristics

Winter steelhead populations generally had higher fecundity estimates than summer steelhead populations due to the larger body size of winter than summer steelhead (Table 12). The mean smolt ages were generally similar between populations, but Meziadin differed from Cranberry, Damdochax and Kwinageese populations. The majority of steelhead were freshwater age 3 and 4. Freshwater age 2 steelhead were rare in most populations except for Meziadin where they consisted of 19 percent of the population. Also, freshwater age 5 steelhead were rare. The majority of steelhead were ocean age 1+ and 2+, whereas ocean age 3+ and 4+ were rare among populations.

Table 12. A summary of the estimated fecundity, mean smolt age (MSA), percentages of repeat spawners, percentage of freshwater (FW) age 2, 3, 4, and 5, and ocean (SW) age 1+, 2+, 3+ and 4+ for steelhead in the Cranberry (Cran.), Kwinageese (Kwin.), Meziadin (Mez.), Ishkheenickh (Ishk.), and Tseax rivers, Damdochax (Damd.) and Chambers (Cham.) creeks and the Nass River fishwheels (Fishwh.). Summer Steelhead Winter Steelhead Cran. Damd. Kwin. Mez. Fishwh. Cham. Ishk. Tseax (1996) Estimated fecundity 2597 3079 2908 2816 2605 4264 3594 2933 (eggs/fish) MSA (years) 3.53 3.74 3.53 3.00 3.27 NA 3.44 3.40 Repeat spawners (%) 5 13 5 6 4 NA 23 12 FW age 2 (%) 0 4 0 19 0 NA 0 0 FW age 3 (%) 48 22 47 62 73 NA 56 62 FW age 4 (%) 51 70 53 19 27 NA 44 38 FW age 5 (%) 1 4 NA NA 0 NA 0 0 SW age 1+ (%) 45 10 44 50 26 NA 24 47 SW age 2+ (%) 50 74 48 44 67 NA 66 41 SW age 3+ (%) 3 10 8 6 5 NA 5 12 SW age 4+ (%) 2 6 0 0 2 NA 5 0 For winter steelhead populations, ocean age 1, 2, 3 and 4 were placed in the 1+, 2+, 3+ and 4+ categories.

25 Nass River steelhead life history characteristics

4.2.0.0 Steelhead Productivity and Allowable Harvest Rates

4.2.1.0 Biostandards Used by Tautz et al. (1992)

Steelhead productivity (equation 6) was examined for semelparous (excluding repeat spawners) life history conditions. However repeat spawners were included in the estimates of mean female length, since scale age data did not exist for many steelhead. The most productive summer steelhead population was the Meziadin (A = 0.95) and the least productive populations were the Cranberry and Damdochax (A = 0.89; Table 13). The productivity of Kwinageese (A = 0.91) summer steelhead was similar to Cranberry and Damdochax steelhead (Table 13). The productivity of summer steelhead was generally less productive than winter steelhead. For winter steelhead, Ishkheenickh steelhead (A = 0.95) were more productive than Tseax steelhead (A = 0.93; Table 13). The mean smolt age of Chambers Creek winter steelhead was unknown, since scale age data did not exist. If the mid-point of the mean smolt age of Ishkheenickh and Tseax river steelhead was used as an estimate for Chambers Creek, then the productivity of Chambers steelhead (A = 0.96) was higher than both Ishkheenickh and Tseax steelhead (Table 13).

For summer steelhead, the allowable harvest rates (equation 5) ranged from a low of 66 percent for Cranberry steelhead to a high of 79 percent for Meziadin steelhead (Table 13). The allowable harvest rates for Damdochax (67%) and Kwinageese (70%) steelhead were similar to Cranberry steelhead (66%). The allowable harvest rates for Ishkheenickh and Tseax river steelhead were 77 and 73 percent, respectively (Table 13). Chambers Creek steelhead had an allowable harvest rate of 81 percent when the estimated mean smolt age was 3.41 years.

Population (yr) n (cm) n RPS µmsy A Summer steelhead Cranberry 3.53 131 68.7 71 2.97 0.66 0.89 Damdochax 3.74 27 74.5 32 3.03 0.67 0.89 Kwinageese 3.53 57 72.5 30 3.33 0.70 0.91 Meziadin 3.00 16 71.4 10 4.71 0.79 0.95 Winter steelhead Chambers 3.411 0 87.0 4 5.32 0.81 0.96 Ishkheenickh 3.44 18 80.2 18 4.39 0.77 0.95 Tseax 3.38 16 72.8 4 3.74 0.73 0.93 Pooled summer steelhead Fishwheels (1996) 3.27 325 68.8 202 3.59 0.72 0.92 1. Chambers Creek mean smolt age was estimated as the mid-point of Ishkheenickh and Tseax rivers.

26 Nass River steelhead life history characteristics

4.2.2.0 Updated Biostandards

Steelhead productivity was examined for semelparous (excluding repeat spawners) life history conditions with updated biostandards (egg-to-fry and smolt-to- adult survival) from Keogh River winter steelhead. The updated biostandards produced lower estimates of recruits per spawner, allowable harvest rates and Beverton-Holt A values than estimates yielded from the biostandards used by Tautz et al. (1992; Table 14). The number of recruits per spawner (equation 4) were less than half (42%) of the estimates from the Tautz et al. (1992) biostandards. The allowable harvest rates and Beverton-Holt A values were reduced by up to 70 and 61 percent of the estimates calculated from the Tautz et al. (1992) biostandards (Table 14). For summer steelhead populations, Meziadin was the most productive and Cranberry was the least productive whereas for winter steelhead populations, Chambers was the most productive and Tseax was the least productive.

Age Length µmsy A Population (yr) n (cm) n RPS (% change) (% change) Summer steelhead Cranberry 3.53 131 68.7 71 1.24 0.20 (-70%) 0.35 (-61%) Damdochax 3.74 27 74.5 32 1.27 0.21 (-69%) 0.38 (-57%) Kwinageese 3.53 57 72.5 30 1.39 0.28 (-60%) 0.48 (-47%) Meziadin 3.00 16 71.4 10 1.97 0.49 (-38%) 0.74 (-22%) Winter steelhead Chambers 3.411 0 87.0 4 2.23 0.55 (-32%) 0.80 (-17%) Ishkheenickh 3.44 18 80.2 18 1.84 0.46 (-40%) 0.70 (-26%) Tseax 3.38 16 72.8 4 1.57 0.36 (-51%) 0.59 (-37%) Pooled summer steelhead Fishwheels (1996) 3.27 325 68.8 202 1.50 0.34 (-53%) 0.56 (-39%) 1. Chambers Creek mean smolt age was estimated as the mid-point of Ishkheenickh and Tseax rivers.

27 Nass River steelhead life history characteristics

4.3.0.0 Uncertainty and Sensitivity Analysis

4.3.1.0 Uncertainty

The median values from the Monte Carlo simulations were similar to the life history model estimates calculated using the mean and geometric mean life history parameters (Table 15). However, the Monte Carlo simulations and frequency distributions illustrated the median and mean values were not in the categories that contained the most frequent (probable) life history model estimates. The skewed graphical distributions of allowable harvest rates and Beverton-Holt A values illustrated strong outliers (Figure 12). These large negative outliers biased the mean estimated allowable harvest rate and Beverton-Holt A value and therefore, the median estimates are more appropriate estimators than the mean estimates.

The uncertainty in the life history model estimates, as indicated by the frequency distribution of the results, followed a similar pattern between Nass River steelhead populations. Therefore the results from the simulation for Cranberry River (Figure 12) were discussed but the same general patterns existed for the other populations (Appendix B-H). Estimates of recruits per spawner greater than 0 and less than 1 illustrated conditions where the population failed to meet sufficient recruitment levels for replacement due to natural (random) variability (Figure 12A). These conditions led to negative harvest rate and Beverton-Holt A value estimates. The probability of these conditions occurring differed between populations where the lower productivity populations had higher chances of not achieving replacement levels. The higher chances of the least productive populations (Cranberry and Damdochax) not meeting the replacement requirements suggested they may be more sensitive to harvest pressures than the more productive populations (Chambers and Meziadin; Table 15).

Beverton-Holt’s A value had the widest range of estimates, but the frequency distribution implied higher estimates near 1 were more likely than lower estimates near 0 (Figure 12C). The simulations for recruits per spawner indicated that random variation resulting from sampling and environmental variability may lead to conditions where the populations produced insufficient recruitment for replacement (Table 15). The distribution of recruits per spawner was negatively skewed (Figure 12A) and indicated the categories with the highest probabilities were for conditions where the recruits per spawner were insufficient for replacement. Allowable harvest rates estimates were negatively skewed (Figure 12B), with the frequencies increasing near 0.66 and then decreasing near 1.

Table 15. Monte Carlo estimates and model sensitivities of recruits per spawner, allowable harvest rates and Beverton-Holt’s A value calculated with updated Keogh River biostandards for steelhead in Chambers Creek, the Nass River fishwheels (1996), Cranberry River, Damdochax Creek and Kwinageese, Meziadin, Ishkheenickh and Tseax rivers. Life History Model Summer Steelhead Winter Steelhead Parameter Cran. Damd. Kwin. Mez. Fishwheels Cham*. Ishk. Tseax Number of trials 10000 10000 10000 10000 10000 10000 10000 10000 Recruits Per Median 1.26 1.28 1.42 1.95 1.46 2.17 1.78 1.53 Spawner (RPS) Mean 2.17 2.17 2.36 3.33 2.44 3.63 2.98 2.62 Standard error 0.03 0.03 0.03 0.05 0.03 0.05 0.04 0.04 Standard deviation 3.09 2.87 3.10 4.70 3.29 5.06 4.16 3.64 Number of trials 4092 4035 3661 2580 3512 2142 2805 3350 with RPS < 1 Allowable Median 0.20 0.22 0.29 0.49 0.31 0.54 0.44 0.35 Harvest Mean -0.35 -0.31 -0.21 0.12 -0.13 0.27 0.08 -0.12 Rate Standard error 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.02 Standard deviation 1.76 1.79 1.71 1.25 1.49 0.88 1.13 2.05 Beverton-Holt’s Median 0.37 0.39 0.50 0.74 0.53 0.79 0.69 0.58 A Value Mean -3.91 -3.91 -3.38 -1.35 -2.50 -0.32 -1.12 -4.44 Standard error 0.23 0.29 0.36 0.20 0.29 0.06 0.09 1.87 Standard deviation 23.13 28.99 36.11 20.24 28.94 6.32 8.78 186.6 Sensitivity Smolt-Adult Surv. 0.67 0.68 0.68 0.65 0.68 0.69 0.68 0.67 (Rank correlation) Egg-Fry Surv. 0.54 0.54 0.55 0.52 0.55 0.56 0.56 0.56 Mean Smolt Age -0.34 -0.39 -0.35 -0.42 -0.32 -0.35 -0.35 -0.33 Female Length 0.27 0.16 0.24 0.21 0.26 0.12 0.20 0.27 Contribution to Smolt-Adult Surv. 47.9 49.6 48.9 46.5 49.5 51.0 44.7 47.8 Variance (%) Egg-Fry Surv. 31.6 31.6 31.9 29.6 32.4 34.1 33.1 33.0 Mean Smolt Age 12.7 16.1 13.2 19.1 11.1 11.1 13.0 11.5 Female Length 7.8 2.7 6.1 4.8 7.0 7 4.1 4.8 * Scale age data were not available for Chambers Creek steelhead, therefore the mean smolt age was estimated as the midpoint of Ishkheenickh and Tseax steelhead (3.41 years, standard deviation = 0.50 years).

Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 199 Outliers .057 574

.043 430

.029 287

.014 143

.000 0

0.00 2.75 5.50 8.25 11.00 Certainty is 40.92% from -Infinity to 1.00 Steelhead B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 376 Outliers .043 434

.033 325

.022 217

.011 108

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 1,608 Outliers .111 1112

.083 834

.056 556

.028 278

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

30 Nass River steelhead life history characteristics

4.3.2.0 Sensitivity

Four different modeling scenarios were compared to examine the relative effects of variability in biostandards (egg-to-fry and smolt-to-adult survival) on the life history model estimates and how the variability affected parameter sensitivity. The first scenario assumed egg-to-fry and smolt-to-adult survival rates were Poisson distributed (10% and 12%, respectively). The Poisson distribution was used because rates (proportions) could be described with a Poisson distribution (Sargent and Wainwright 1996). The second scenario differed from the first by using observed egg-to-fry survival rates from the Keogh River (Ward and Slaney 1993; 1976-1982) and assumed the data were lognormally distributed. Bradford (1995) examined the distributions of egg-to-fry survivals of Pacific salmon and concluded the survival rates could be described with a lognormal distribution. The third scenario differed from the first by using observed smolt-to-adult survival from the Keogh River (Ward and Slaney 1988; B. Ward, personal communication; 1976- 1993). Peterman (1981) and Bradford (1995) examined the smolt-to-adult survival rates in Pacific salmon and concluded the rates could be described with a lognormal distribution. The fourth scenario differed from the first by using observed egg-to-fry and smolt-to-adult survival data from the Keogh River and developing a probability distribution for those values.

Table 16. Effects of variability in life history model parameters on the probability of Cranberry River steelhead having insufficient recruits per spawner for replacement (RPS<1) and the effects on model sensitivity and variance in life history model estimates. Parameter Scenario 1 2 3 4 Number of trials 10000 10000 10000 10000 Number of trials 1182 3429 2237 4092 with RPS < 1 (Percentage with 11.8% 34.3% 22.4% 40.9% recruitment failure) Sensitivity Smolt-Adult Surv. 0.44 0.36 0.76 0.67 (Rank correlation) Egg-Fry Surv. 0.49 0.69 0.37 0.54 Mean Smolt Age -0.53 -0.44 -0.39 -0.34 Female Length 0.42 0.35 0.30 0.27 Contribution to Smolt-Adult Surv. 21.8 13.8 60.6 47.9 Variance (%) Egg-Fry Surv. 26.4 51.8 14.3 31.6 Mean Smolt Age 31.9 20.9 15.7 12.7 Female Length 19.9 13.5 9.4 7.8

Variability in egg-to-fry survival had a larger effect on increasing the chances of the population having insufficient recruitment for replacement (scenario 2) than smolt-to-adult survival (scenario 3; Table 16). As expected, when the variability of both parameters was included (scenario 4), the chances of the population having insufficient recruitment for replacement were much greater (approximately four fold) than the scenario where the biostandard variability was excluded (scenario 1; Table 16). Therefore by excluding the variability in the biostandards, the life history model estimates may be overestimated and resemble the ‘stable environment’ conditions

31 Nass River steelhead life history characteristics rather than the average estimates expected for environmental conditions that existed when the data were collected.

In the absence of observed variability in biostandards (scenario 1), mean smolt age was the most sensitive parameter, followed by egg-to-fry survival, smolt- to-adult survival and female length (Table 16). When the variability of the biostandards was included separately (scenarios 2 and 3), the biostandard became the most sensitive parameter, but mean smolt age was the second most sensitive parameter and female length was the least sensitive parameter for both conditions (Table 16). When the variability in egg-to-fry and smolt-to-adult survival was modeled (scenario 4), smolt-to-adult survival was the most sensitive parameter followed by egg-to-fry survival, mean smolt age and female length (Table 16).

Errors in mean smolt age were investigated by increasing the mean smolt age value by 0.2 year increments. The 0.2 year increment approximates the error in the life history model estimates if 20 percent of the steelhead were under-aged by one year. Hooton et al. (1987) and Tautz et al. (1992) discussed the negative bias in the freshwater ages determined from adult scales for steelhead rearing in streams with short growing seasons.

MSA RPS A µmsy (%) 3.33 3.43 0.92 71 3.53 2.97 0.89 66 3.73 2.57 0.85 61 3.93 2.23 0.80 55 4.13 1.93 0.73 48 4.33 1.67 0.64 40 4.53 1.45 0.52 31

Errors in estimating the mean smolt age from adult scales may have a pronounced effect on the life history model estimates (Table 17). Since adult scales were suspected to have a negative bias in freshwater ages, improved scale reading techniques or adjustments for a missing first annulus may demonstrate that the current mean smolt age was underestimated. Thus, if the actual mean smolt age was older than current estimates, then the number of recruits per spawner, stock productivity and allowable harvest rate estimates would currently be overestimated (Table 17). An ultra-conservative approach must be used when interpreting the life history model estimates since these negative biases in mean smolt age probably exist in the current estimates.

32 Nass River steelhead life history characteristics

5.0.0.0 Discussion

5.1.0.0 Life History Characteristics

The similar size of male and female Nass River steelhead was inconsistent with the results of other studies. However, males were larger than females for ocean age 1+ Cranberry River steelhead, ocean age 2+ Kwinageese River steelhead and ocean age 2+ steelhead sampled at the Nass River fishwheels in 1996. Steelhead were not pooled among rivers because the size at ocean age may differ between rivers for summer and winter steelhead populations (Hooton et al. 1987). Size differences between males and females may have been compromised by pooling steelhead among years and ocean ages, since the proportion of the returning adult population in different ocean age groups may vary between years and sexes (Whately 1977; Chudyk et al. 1977; Whately et al. 1978; Chudyk and Whately 1980; O’Neill and Whately 1984; Hooton et al. 1987; Ward and Slaney 1988). Larger males than females at a given ocean age were similar to the results reported for Skeena River steelhead in the Tyee test fishery (Chudyk 1976), Kitsumkalum River (Lough and Whately 1984), Kispiox River steelhead (Whately 1977), Babine River (Narver 1969), as well as steelhead in Copper Creek (Chudyk and Walsh 1982; Queen Charlotte Islands (QCI)), Yakoun River (de Leeuw 1987; QCI), Vancouver Island (Hooton et al. 1987) and Keogh River (Ward and Slaney 1988).

The length of adult steelhead in the Cranberry, Kwinageese, and Meziadin rivers and Nass River fishwheels (1996) increased with ocean age, consistent with the results of other studies. Summer steelhead sampled in the Tyee test fishery (Chudyk 1976) and in the Zymoetz River (Chudyk and Whately 1980) also increased in adult length with increases in ocean age. For winter steelhead on the Queen Charlottes, adult steelhead length increased with ocean age in the Yakoun River (de Leeuw 1987) and Copper Creek (Chudyk and Walsh 1982). Similarly, summer and winter steelhead from Vancouver Island also increased in length with ocean age (Hooton et al. 1987). Ward and Slaney (1988) also reported adult length increased with ocean age for Keogh River winter steelhead.

Adult size was similar between freshwater ages for summer steelhead in the Cranberry, Damdochax and Meziadin rivers and Nass River fishwheels (1996), but increased with freshwater age for Kwinageese steelhead. In the Kalama River, Washington, Leider et al. (1986) reported similar adult lengths between freshwater ages for summer and winter steelhead. Chudyk (1976) reported Skeena River summer steelhead length increased with freshwater age. Although, Ward and Slaney (1988) reported the size of adult Keogh River steelhead decreased as freshwater age increased, but noted that adult length increased with freshwater age for ocean age 2+ steelhead and was similar between freshwater ages for ocean age 3+ steelhead. Sample sizes from some Nass River tributaries were too small to permit similar statistical comparisons within ocean age groups. Since tributary

33 Nass River steelhead life history characteristics samples were pooled across years, the inter-annual variation in adult length may have compromised the differences between freshwater age categories (Leider et al. 1986; Hooton et al. 1987).

Damdochax Creek steelhead were similar in size to Kwinageese and Meziadin river steelhead, but larger than Cranberry River steelhead. Therefore, differences in adult size may exist between Nass River populations. The results should be considered cautiously until sample sizes within returning adult years are large enough to compare lengths between different populations, but within an ocean age group. The differences may reflect variation in the proportion of ocean aged adults or variation in recruitment, since the data were pooled among years and not all tributaries were sampled during the same year.

The range in the estimated fecundity of Nass River summer steelhead was generally lower than the range for Skeena River summer steelhead. In the Nass River, estimated fecundity ranged from 2597 eggs/fish (Cranberry River) to 3079 eggs/fish (Damdochax Creek). Sebastian (1987) estimated the average fecundity of Cranberry River steelhead was 2300 eggs/fish. Similar estimates of fecundity were reported for other Skeena River tributary populations: Kitwanga and Kitseguecla (2615 eggs/fish), upper Sustut and Kluatantan (2644 eggs/fish), Babine (2762 eggs/fish), lower Sustut (2853 eggs/fish) and Kispiox (2906 eggs/fish; Tautz et al. 1992). Other Skeena River summer steelhead populations had lower estimated fecundities than Nass River summer steelhead (i.e. Morice = 1868, Bulkley = 2374, Zymoetz = 2444; Tautz et al. 1992). The range in fecundity of Nass River winter steelhead (Tseax = 2933 to Chambers = 4264 eggs/fish) was higher than the range estimated for Skeena River summer steelhead (Tautz et al. 1992).

The frequency of repeat spawning summer steelhead in the Nass River was similar to the results reported from the Skeena River. The frequency of repeat spawning summer steelhead ranged from 5 percent (Cranberry and Kwinageese) to 13 percent (Damdochax) in the Nass watershed. The low percentage of repeat spawning summer steelhead in the Nass River was similar to the results reported for Skeena River steelhead populations in the Sustut River (1.2-6%; Saimoto 1995, Parken and Morten 1996), Kitsumkalum River (2.6%; Lough and Whately 1984), Bulkley River (3.4%; O’Neill and Whately 1984), Suskwa River (3.8%; Chudyk 1978), Morice River (6.6%; Whately et al. 1978) and Babine River (6.9%; Narver 1969; Whately and Chudyk 1979). However, the percentage of repeat spawners was reported to be substantially higher in the Kispiox River (17.6%; Whately 1977) and the Zymoetz River (29%; Chudyk and Whately 1980). Hooton et al. (1987) reported approximately 7 percent of Vancouver Island summer steelhead were repeat spawners which was similar to the 6 percent reported for Kalama River summer steelhead (Leider et al. 1986). Comparisons of the frequency of repeat spawners between rivers should be made cautiously because the sampling occurred during different time periods and the results may partially reflect variable recruitment or ocean survival (Ward and Slaney 1988).

34 Nass River steelhead life history characteristics

A higher percentage of repeat spawners observed in winter than summer steelhead in the Nass River was similar to the results reported for steelhead in other areas. Hooton et al. (1987) reported a higher percentage of repeat spawners among winter (10%) than summer (7%) steelhead on Vancouver Island. Similarly, Leider et al. (1986) reported winter steelhead had a higher percentage of repeat spawners (11%) than summer steelhead (6%) in the Kalama River, Washington. Among winter steelhead, the percentage of repeat spawners ranged from 12 (Tseax) to 23 percent (Ishkheenickh) in the Nass River tributaries. In the Queen Charlotte Islands, the percentage of repeat spawners for winter run steelhead was 4.5 percent in the Mamin River (de Leeuw 1986a), 12.1 percent in the Yakoun River (de Leeuw 1987) and 25.6 percent in Deena Creek (de Leeuw 1986b). Repeat spawner frequencies among Nass River winter steelhead were similar to results reported from the Keogh River (8.1% for males and 11.6% for females; Ward and Slaney 1988), but lower than results from Petersburg Creek, Alaska (38.3%; Jones 1977).

The range in mean smolt age, as calculated from adult scales, from the Nass River was generally lower than the range reported from the Skeena River. The mean smolt age of Nass River summer steelhead ranged from 3.00 years in the Meziadin River to 3.74 years in the Damdochax Creek. Skeena River summer steelhead ranged in smolt age from 3.45 years (Buck Creek) to 5.68 years (Goathorn Creek; Bocking and English 1992). The mean smolt age of Cranberry River steelhead from adult scales (3.53 years) was slightly higher than Sebastian’s (1987) mean smolt age estimate (3.30 years) based on the length of the growth season. Tautz et al. (1992) estimated the mean smolt age of Skeena River summer steelhead ranged from 3.3 years (Babine River) to 4.5 years (upper Sustut River) based on the length of the growth season.

The mean smolt age of Nass River steelhead should be interpreted cautiously because of the limitations in freshwater aging. For example, some proportion of steelhead may not have formed scales during the first year (Jensen and Johnsen 1982; Hooton et al. 1987) or may not have formed the fist annulus because of short growing seasons in rearing areas (Hooton et al. 1987; Tautz et al. 1992; Triton 1994a, 1994b).

5.2.0.0 Steelhead Productivity and Allowable Harvest Rates

The range of productivities and allowable harvest rates for Nass River summer steelhead populations were similar to the range described for Skeena River summer steelhead by Tautz et al. (1992) when calculations were made with identical biostandards. However, comparisons between the Nass and Skeena rivers should be made cautiously because the mean smolt age of Nass River steelhead was estimated from adult scales whereas the mean smolt age of Skeena River steelhead was estimated from growth season data. Bocking and English (1992) illustrated that mean smolt age predicted from the growth season length was slightly lower than

35 Nass River steelhead life history characteristics estimates from adult scales and thus, the growth season predictor may overestimate productivity and allowable harvest rates (Tautz et al. 1992).

The productivity of Nass River summer steelhead ranged from a low in Cranberry River and Damdochax Creek (A = 0.89) to a high in Meziadin River (A = 0.95). In the Skeena River, steelhead from the upper and lower Sustut (A = 0.54, 0.73 respectively), Kitwanga (A = 0.64), Morice (A = 0.67), Zymoetz (A = 0.73), Kitseguecla (A = 0.83) and Suskwa (A = 0.84) rivers were less productive than Nass River summer steelhead (Tautz et al. 1992). Nass River steelhead productivities were similar to steelhead in the Bulkley (A = 0.87), Kispiox (A = 0.88) and Babine (A = 0.93) rivers (Tautz et al. 1992).

Nass River winter steelhead had similar productivity estimates (A value range, 0.93 to 0.96) to Keogh River winter steelhead and Babine River summer steelhead. In the Keogh River, winter steelhead productivity (A=0.93) was estimated from observed spawner and recruit abundances (Ward 1996). Tseax (A = 0.93) and Ishkheenickh (A = 0.95) steelhead had higher productivity estimates than Skeena River summer steelhead in the Suskwa, Bulkley and Kispiox rivers. When the mean smolt age was estimated at 3.41 years, Chambers Creek steelhead had a higher productivity estimate (A = 0.96) than Babine River steelhead (A = 0.93; Tautz et al. 1992). Nass River winter steelhead had higher productivity estimates than Nass River summer steelhead because female winter steelhead were larger than summer steelhead, which resulted in higher fecundity estimates. On Vancouver Island, Hooton et al. (1987) also reported winter steelhead were larger than summer steelhead.

The range of allowable harvest rates estimated for Nass River summer steelhead were similar to the results for Skeena River summer steelhead. Allowable harvest rates of Cranberry (µmsy = 0.66), Damdochax (µmsy = 0.67), Kwinageese (µmsy =

0.70) and Meziadin (µmsy = 0.70) steelhead were similar to estimates for Bulkley (µmsy

= 0.65), Kispiox (µmsy = 0.66) and Babine (µmsy = 0.73) steelhead (Tautz et al. 1992). Nass River summer steelhead had higher allowable harvest rates than upper Sustut

(µmsy = 0.32), Kluatantan (µmsy = 0.39), Kitwanga (µmsy = 0.40), Morice (µmsy = 0.43), lower Sustut and Zymoetz (µmsy = 0.48), Kitseguecla (µmsy = 0.58) and Suskwa (µs = 0.60) steelhead (Tautz et al. 1992). Sebastian (1987) suggested Cranberry steelhead may be fairly susceptible to overharvest, but did not estimate a sustainable harvest rate.

Allowable harvest rate estimates for winter steelhead in the Tseax (µmsy =

0.73) and Ishkheenickh (µmsy = 0.77) rivers were similar to the estimates for Keogh

River winter steelhead (µmsy = 0.74; estimated from observed stock-recruitment data;

Ward 1996) and Babine River summer steelhead (µmsy = 0.73; Tautz et al. 1992). When the mean smolt age was estimated at 3.41 years for Chambers Creek, the allowable harvest rate (µmsy = 0.81) was higher than the results reported for Babine River summer steelhead (Tautz et al. 1992).

36 Nass River steelhead life history characteristics

Stock-recruitment estimates from modeling exercises should always be interpreted cautiously when large assumptions are made regarding the data the model was based on (Hilborn and Walters 1992; NRC 1996). Stock recruitment analysis for Nass River steelhead was based on life history parameters measured for Keogh River winter steelhead and fecundities based on Skeena River summer steelhead. Large geographical and life history differences may exist between Nass and Keogh river steelhead, and therefore the results must be interpreted cautiously and the model results should only be used in an ultra-conservative fashion until they can be substantiated. Ward (1996) cautioned that stock-recruitment analysis of steelhead was influenced by environmental variability and age-at-return variation and that these factors decreased the stock-recruitment model’s ability to predict the abundance of returning adults. Ward (1996) also demonstrated that stock recruitment parameters estimated in the absence of environmental variability overestimated allowable harvest rates, but cautioned that simple inclusion of the variability continued to produce harvest rate estimates that would lead to over- exploitation in some years. Iteroparity, variable age-at-return, and variable smolt age may be evolutionary strategies of steelhead that counter the effects of variable adult returns resulting from environmental variation (Hooton et al. 1987; NRC 1996).

5.3.0.0 Uncertainty and Sensitivity Analysis

Monte Carlo simulations indicated a wide range in the variability around estimates of recruits per spawner, allowable harvest rates and Beverton-Holt A values. The distributions were skewed and resembled the variability of the two most sensitive parameters (smolt-to-adult and egg-to-fry survival). The median values from the simulations were similar to the estimates calculated from the updated biostandards, however median and mean values did not occur in the frequency categories with the highest probabilities. Insufficient recruitment levels for replacement in some years (trials), as predicted by the simulations, was consistent with the results observed at the Keogh River (Ward 1996). Monte Carlo simulation results resembled the measurement and environmental variability that existed when the data were collected (NRC 1996).

Smolt-to-adult survival was the most sensitive parameter followed by egg-to- fry survival, mean smolt age and female length when the updated biostandards were used. The high variability in smolt-to-adult and egg-to-fry survival (approximately an order of magnitude) contributed to the higher sensitivity for these parameters than mean smolt age and female length. When the variability in the biostandards was excluded, mean smolt age was the most sensitive parameter for estimating the life history model estimates which was consistent with the results of Bocking and English (1992). Although mean smolt age was not as sensitive as the biostandards, small changes may have substantial effects on the life history model estimates. Current estimates of mean smolt age were likely underestimated for populations that rear in streams with short growing seasons (Hooton et al. 1987; Tautz et al. 1992). Thus, the actual mean smolt age estimates for some Nass River tributaries may be

37 Nass River steelhead life history characteristics higher and the life history model estimates may be lower than the estimates based on adult scales. Until the negative bias in adult scale ages is examined for Nass River steelhead, an ultra-conservative approach should be used when interpreting the life history model estimates.

38 Nass River steelhead life history characteristics

6.0.0.0 Recommendations

1. Future research should examine the relationship between the number of circuli formed and length of growth season (G7), the proportion of steelhead in a year class that form a first annulus with G7, the proportion of steelhead that form scales by G7 and fork length.

2. Future research should validate smolt ages determined from adult scales. Also, each of the negative biases and their interaction with growth season length should be investigated. Research should focus on developing a correction factor (or equation) for the percentage of steelhead without a distinguishable first annulus or that do not form scales in their first year with the length of the growth season (possibly measured by G7, G6.5, or degree days). Alternatively, the research may focus on improving the scale reading methods for streams with short growth seasons.

3. Since the data from adult scales were influential in the Nass habitat capability model estimates, some level of quality control and quality assurance in scale aging must be maintained to decrease the variance in scale ages between different scale aging agencies.

4. Distinctions must be made between summer and winter steelhead in rivers that harbor sympatric populations.

5. A fecundity regression should be developed for Nass River summer and winter steelhead (possibly separate regressions if samples are sufficient). Data sources include the Nisga’a Tribal Council catch monitoring program and mortalities at the fishwheels.

6. Steelhead captured at the fishwheels should be marked with a numbered tag. Tag recoveries in the tributaries and catch monitoring programs could help describe run-timing and in-river exploitation rates.

7. Detailed population and biostandard monitoring should be continued at the Keogh River to help refine the Nass habitat capability model estimates.

8. Life history model estimates should be recalculated when new data are available.

39 Nass River steelhead life history characteristics

7.0.0.0 Acknowledgments

A large portion of the data summarized in the report were the result of numerous person-years of effort by Fisheries Branch staff of the Ministry of Environment, Lands and Parks. The direction, coordination and efforts of all staff involved over the years was appreciated. I thank Ron Tetreau for aging steelhead scales in a timely fashion and assistance with the MOELP scale archives. Bob Bocking, Bill Koski, Michael Link, LGL Ltd. and the Nisga’a Tribal Council are thanked for providing data for steelhead sampled at the fishwheels and the 1993 telemetry project. I thank Ken Belford for collecting steelhead samples from Damdochax Creek. Bruce Ward provided the egg-to-fry survival and smolt-to-adult survival data from Keogh River winter steelhead. I thank Krista Morten for assistance with data entry, data analysis and suggestions on earlier drafts. I thank Dana Atagi for assistance with the Skeena Region MOELP branch files and for the many useful comments and advice during data analysis and critical reviews. I thank Dr. Ted Down for securing funding for the preparation of this review. Funding for the preparation of this review was provided by the Common Land Information Base.

40 Nass River steelhead life history characteristics

8.0.0.0 Literature Cited

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Anonymous. 1996. SPSS Base 7.0 for Windows users guide. SPSS Inc., Chicago, IL. 564 p.

Bjornn, T.C. 1987. A life history model for predicting the abundance and yield of anadromous salmonids. Idaho Cooperative Fish and Wildlife Resources Unit, Technical Report 87-2: 42 p.

Bocking, R.C. 1997. (Personal Communication; Fisheries Biologist; LGL Ltd., Sidney, B.C.)

Bocking, R.C. and K.K. English. 1992. Evaluation of the Skeena steelhead habitat model. Report by LGL. Ltd., Sidney, B.C. for Fisheries Branch, B.C. Ministry of Environment, Lands and Parks. Victoria, B.C.

Bocking, R.C. and K.K. English. 1993. Nass River sport fishery catch monitoring program, 1992. Report by LGL Ltd., Sidney, B.C. for the Nisga’a Tribal Council, New Aiyansh, B.C. Nisga’a Fisheries Report NF92-05.

Bocking, R.C. and K.K. English. 1994a. Nass River sport fishery catch monitoring program, 1993. Report by LGL Ltd., Sidney, B.C. for the Nisga’a Tribal Council, New Aiyansh, B.C. Nisga’a Fisheries Report NF93-04.

Bocking, R.C. and K.K. English. 1994b. Nass River catch monitoring program, 1993 Nisga’a Fishery. Report by LGL Ltd., Sidney, B.C. for the Nisga’a Tribal Council, New Aiyansh, B.C. Nisga’a Fisheries Report NF93-03.

Bradford, M.J. 1995. Comparative review of Pacific salmon survival rates. Canadian Journal of Fisheries and Aquatic Sciences 52:1327-1338.

Burgner, R.L., J.T. Light, L. Margolis, T. Okazaki, A. Tautz, and S. Ito. 1992. Distribution and origins of steelhead trout (Oncorhynchus mykiss) in offshore waters of the north Pacific Ocean. International North Pacific Fisheries Commission. Bulletin Number 51. Vancouver, B.C.

Bustard, D. 1995. Fisheries assessment and stream classification of Chambers Creek. Report by David Bustard and Associates for Skeena Sawmills Ltd., Terrace, B.C.

41 Nass River steelhead life history characteristics

Chambers, J.M., W.S. Cleveland, B. Kleiner and P.A. Tukey. 1983. Graphical methods for data analysis. Wadsorth Int. Group, Duxbury Press, Belmont, CA. 395 p.

Chudyk, W.E. 1976. The life history of adult steelhead sampled in the Tyee test fishery in the Skeena River estuary and comparisons with other steelhead stocks in British Columbia. British Columbia Ministry of Environment, Lands and Parks. Fish and Wildlife Branch. Skeena Fisheries Report SK#2.

Chudyk, W.E. 1978. Suskwa River steelhead trout: the 1977 inventory, creel survey and life history characteristics study leading to the removal of a barrier on Harold-Price Creek. British Columbia Ministry of Environment, Lands and Parks. Fish and Wildlife Branch. Skeena Fisheries Report SK#15.

Chudyk, W.E. and M. Walsh. 1982. Copper Creek (Q.C.I.) steelhead trout: a report on the effect of non random release of kelts from a fence barrier on their incidental capture in an Indian net fishery, and some notes on population size and life history characteristics. British Columbia Ministry of Environment, Lands and Parks. Fish and Wildlife Branch. Skeena Fisheries Report SK#36.

Chudyk, W.E. and M.R. Whately. 1980. Zymoetz and Clore River steelhead trout: a report on the 1978 and 1979 sport fishery and some aspects of their life history. British Columbia Ministry of Environment, Lands and Parks. Fish and Wildlife Branch. Skeena Fisheries Report SK#27.

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42 Nass River steelhead life history characteristics

Dubios, R.B., S.D. Plaster and P.W. Rasmussen. 1989. Fecundity of spring- and fall-run steelhead from two western Lake Superior tributaries. Transactions of the American Fisheries Society 118:311-316.

Evenson, M.D., and R.D. Ewing. 1992. Migration characteristics of hatchery returns of winter steelhead volitionally released from Cole Rivers Hatchery, Oregon. North American Journal of Fisheries Management 12:736-741.

Haas, G.R. and J.D. McPhail. 1991. Systematics and distributions of Dolly Varden (Salvelinus malma) and bull trout (Salvelinus confluentus) in North America. Canadian Journal of Fisheries and Aquatic Sciences. 48:2191-2211.

Hilborn, R., and C.J. Walters. 1992. Quantitative fisheries stock assessment: choice dynamics and uncertainty. Chapman and Hall, New York.

Hooton, R.S., B.R. Ward, V.A. Lewynski, M.G. Lirette and A.R. Facchin. 1987. Age and growth of steelhead in Vancouver Island populations. Fisheries Branch, B.C. Ministry of Environment, Lands and Parks, Smithers, B.C. Fisheries Technical Circular No. 77.

Jensen, A.J. and B.O. Johnsen. 1982. Difficulties in aging Atlantic salmon (Salmo salar) and brown trout (S. trutta) from cold rivers due to lack of scales as yearlings. Canadian Journal of Fisheries and Aquatic Sciences 39:321-325.

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Koski, W.R. and K.K. English. 1996. Status of Nass River steelhead. Report by LGL. Ltd., Sidney, B.C. for Fisheries Branch, B.C. Ministry of Environment, Lands and Parks. Smithers, B.C.

Leider, S.A., M.W. Chilcote and J.J. Loch. 1986. Comparative life history characteristics of hatchery and wild steelhead trout (Salmo gairdneri) of summer and winter races in the Kalama River, Washington. Canadian Journal of Fisheries and Aquatic Sciences 43:1398-1409.

Link, M.R. 1997. (Personal Communication; Fisheries Biologist; LGL Ltd., Sidney, B.C.)

Link, M.R., K.K. English and R.C. Bocking. 1993. The 1992 fishwheel project on the Nass River and an evaluation of fishwheels as an in-season management and stock assessment tool for the Nass River. Report by LGL Ltd., Sidney, B.C. for the Nisga’a Tribal Council, New Aiyansh, B.C. Nisga’a Fisheries Report NF 92-09.

43 Nass River steelhead life history characteristics

Link, M.R. and K.K. English. 1994. The 1993 fishwheel project on the Nass River and an evaluation of fishwheels as an in-season management and stock assessment tool for the Nass River. Report by LGL Ltd., Sidney, B.C. for the Nisga’a Tribal Council, New Aiyansh, B.C. Nisga’a Fisheries Report NF93- 06.

Link, M.R. 1995. The 1994 fishwheel project on the Nass River and an evaluation of fishwheels as an in-season management and stock assessment tool for the Nass River. Report by LGL Ltd., Sidney, B.C. for the Nisga’a Tribal Council, New Aiyansh, B.C. Nisga’a Fisheries Report NF 94-04.

Lough, M.J. 1983. Radio-telemetry studies of summer steelhead trout in the Cranberry, Kispiox, Kitwanga and Zymoetz rivers and Toboggan Creek, 1980. British Columbia Ministry of Environment, Lands and Parks. Fisheries Branch. Skeena Fisheries Report SK#33.

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Pojar, J. and F.C. Nuzsdorfer. 1988. Biogeoclimatic and ecoregions units of the Prince Rupert Forest Region. Map produced by B.C. Ministry of Forests, Victoria, B.C.

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Ward, B.R. 1997. (Personal Communication; Fisheries Research Scientist. Fisheries Branch, British Columbia Ministry of Environment, Lands and Parks, UBC, Vancouver, B.C.)

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Whately, M.R., W.E. Chudyk and M.C. Morris. 1978. Morice River Steelhead trout: the 1976 and 1977 sport fishery and life history characteristics from anglers’ catches. British Columbia Ministry of Environment, Lands and Parks. Fish and Wildlife Branch. Skeena Fisheries Report SK#14.

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46 Nass River steelhead life history characteristics

8.0 Appendix

Appendix A. Information on adult steelhead and rainbow trout sampled in Nass River tributaries. Steelhead ages were reported with the number of winters spent in freshwater before the decimal point followed by the number of winters spent in the ocean. A + identifies a summer steelhead with some scale growth after its last winter in the ocean. In contrast, winter steelhead do not have a + because they entered freshwater near the end of the winter. An S identifies a previous spawning event and represents 1 ocean year and an R represents regenerated scales that could not be used to determine age. A steelhead age 3.2S1+ was a summer steelhead that spent 3 winters in freshwater before smolting and then spent 2 winters in the ocean before its first spawning run and then spent another winter in the ocean before making its second spawning migration. The steelhead was freshwater age 3 and ocean age 4. Steelhead ages that were not linked to length or sex data were summarized in a box beside the sampling date and related information.

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Bell Irving July 22/1993 s f 76.0 2.2+ Alexander and Koski, 1995 Sept. 14/1995 Bell Irving Aug. 10/1993 s m 74.0 NA Alexander and Koski, 1995 Sept. 14/1995 Chambers May 8-9/94 s f 81.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s f 84.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s f 90.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s f 93.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 59.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 71.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 76.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 78.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 84.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 84.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 89.0 Bustard 1995 Feb. /1995 Chambers May 8-9/94 s m 92.0 Bustard 1995 Feb. /1995 Cranberry Nov. 1/1996 s m 78.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 69.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 68.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 54.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 73.0 4.1S1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 67.0 R.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 78.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 77.0 R.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 59.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 74.0 4.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 68.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 58.0 4.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 73.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 57.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 74.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 78.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 75.0 4.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 66.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 76.0 4.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 60.0 4.1+ Memo to file/DNA sampling Nov. /1996

47 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Cranberry Nov. 1/1996 s m 79.0 4.1S1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 53.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 61.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 81.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 73.0 4.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 72.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 58.0 3.1+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s m 88.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Nov. 1/1996 s f 77.0 3.2+ Memo to file/DNA sampling Nov. /1996 Cranberry Oct. 20/1995 s f 71.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 75.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 85.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 72.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 71.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 83.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 79.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 55.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 73.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 74.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 72.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 76.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 60.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 52.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 62.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 70.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 64.0 raw data/DNA sampling Cranberry Oct. 20/1995 s f 73.0 raw data/DNA sampling Cranberry Oct. 20/1995 s m 76.0 raw data/DNA sampling Cranberry Aug. 30/1993 s m 66.0 3.2+ Alexander and Koski, 1995 Sept. 14/1995 Cranberry Aug. 7/1993 s m 76.0 4.2+ Alexander and Koski, 1995 Sept. 14/1995 Cranberry July 23/1993 s f 71.0 3.2+ Alexander and Koski, 1995 Sept. 14/1995 Cranberry Sept. 30/1993 s f 65.0 NA Alexander and Koski, 1995 Sept. 14/1995 Cranberry 1980/1981 s m 73.7 3.2+ Scale Cards/MOELP files Cranberry 1980/81 s f 74.9 3.2+ Scale Cards/MOELP files Cranberry Oct. 30/1979 s m 76.2 3.2+ Scale Cards/MOELP files Cranberry Oct. 30/1979 s m 58.4 3.1+ Scale Cards/MOELP files Cranberry Oct. 30/1979 s f 73.7 3.2+ Scale Cards/MOELP files Cranberry Oct. 30/1979 s m 55.9 3.1+ Scale Cards/MOELP files Cranberry Oct. 30/1979 s m 53.3 3.1+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s m 73.7 3.1S1+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s m 61.0 4.1+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s f 72.4 3.2+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s f 61.0 4.1+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s f 73.7 3.2+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s f 63.5 4.1+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s f 78.7 3.2+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s f 68.6 3.2+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s m 61.0 3.1+ Scale Cards/MOELP files Cranberry Oct. 31/1979 s f 73.7 4.1+ Scale Cards/MOELP files

48 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Cranberry Oct. 31/1979 s m 71.1 4.2+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s f 55.9 4.1+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s f 53.3 3.1+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s m 61.0 3.1+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s f 73.7 4.2+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s f 53.3 4.1+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s m 66 5.1+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s f 55.9 3.1+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s m 78.7 3.2+ Scale Cards/MOELP files Cranberry Nov. 1/1979 s m ? ? Scale Cards/MOELP files Cranberry Nov. 1/1979 s m 61.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s m 61.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s f 66.0 4.2+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s m 58.4 3.1+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s m 68.6 4.2+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s f 73.7 3.2+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s m 66.0 R.1+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s m 68.6 3.2+ Scale Cards/MOELP files Cranberry Nov. 2/1979 s f 55.9 4.1+ Scale Cards/MOELP files Cranberry Nov. 7/1979 s m 68.6 3.2+ Scale Cards/MOELP files Cranberry Nov. 27/1979 s f 53.3 ? Scale Cards/MOELP files Cranberry Nov. 27/1979 s m 61.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 27/1979 s m 63.5 4.1+ Scale Cards/MOELP files Cranberry Nov. 27/1979 s m 61.0 3.1+ Scale Cards/MOELP files Cranberry Nov. 28/1979 s m 86.4 3.2+ Scale Cards/MOELP files Cranberry Nov. 28/1979 s f 81.3 4.2S1+ Scale Cards/MOELP files Cranberry Nov. 28/1979 s f 54.6 4.1+ Scale Cards/MOELP files Cranberry Nov. 28/1979 s f 71.1 4.2+ Scale Cards/MOELP files Cranberry Nov. 28/1979 s m 55.9 3.1+ Scale Cards/MOELP files Cranberry Nov. 28/1979 s m 63.5 4.1+ Scale Cards/MOELP files Cranberry Nov. 28/1979 s m 81.3 3.2+ Scale Cards/MOELP files Cranberry Sept. 19/1978 s f 73.7 3.2+ Scale Cards/MOELP files Cranberry Sept. 20/1978 s m 83.8 4.2+ Scale Cards/MOELP files Cranberry Sept. 20/1978 s m 86.4 3.2+ Scale Cards/MOELP files Cranberry Sept. 21/1978 s m 83.8 4.2+ Scale Cards/MOELP files Cranberry Sept. 17/1977 s m 78.7 3.2+ Scale Cards/MOELP files Cranberry Nov. 5/1977 s f 81.3 4.2+ Scale Cards/MOELP files Cranberry Nov. 5/1977 s f 88.9 4.2+ Scale Cards/MOELP files Cranberry Nov. 14./1977 s f 71.1 3.2+ Scale Cards/MOELP files Cranberry Nov. 14/1977 s f 81.3 4.2+ Scale Cards/MOELP files Cranberry Nov. 15/1977 s f 78.7 4.2+ Scale Cards/MOELP files Cranberry Nov. 15/1977 s f 71.1 R.2+ Scale Cards/MOELP files Cranberry Nov. 15/1977 s f 73.7 4.2+ Scale Cards/MOELP files Cranberry Nov. 15/1977 s m 58.4 4.1+ Scale Cards/MOELP files Cranberry Nov. 15/1977 s m 58.4 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 55.9 R.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 55.9 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s m 86.7 4.2+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s m 73.7 4.2+ Scale Cards/MOELP files

49 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Cranberry Nov. 16/1977 s f 61.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s m 66.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 55.9 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 78.7 4.2+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s m 66.0 4.2+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 61.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 61.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 55.9 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 73.7 4.2+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s m 58.4 4.1+ Scale Cards/MOELP files Cranberry Nov. 16/1977 s f 76.2 3.2+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 58.4 4.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 63.5 3.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s f 86.4 4.2S1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s f 58.4 4.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 58.4 4.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s f 86.4 4.2S1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 r 26.5 5 Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 69.8 4.2+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 66.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 83.8 4.2+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 66.0 3.2+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 86.4 4.2+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 58.4 4.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 61.0 3.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 66.0 4.1+ Scale Cards/MOELP files Cranberry Nov. 17/1977 s m 63.5 3.1+ Scale Cards/MOELP files Cranberry Oct. 3/1977 s m 59.0 3.1+ Scale Cards/MOELP files Cranberry April 2/1978 s f 77.0 3.2+ Scale Cards/MOELP files Cranberry April 2/1978 s f 74.0 3.2+ Scale Cards/MOELP files Cranberry April 2/1978 s m 62.0 4.1+ Scale Cards/MOELP files Cranberry April 2/1978 s m 63.0 4.2+ Scale Cards/MOELP files Cranberry April 2/1978 s f 71.0 3.1S1+ Scale Cards/MOELP files Cranberry April 16/1978 s f 73.7 4.2+ Scale Cards/MOELP files Cranberry April 16/1978 s m 81.3 3.2+ Scale Cards/MOELP files Cranberry April 16/1978 s f 55.9 4.1+ Scale Cards/MOELP files Cranberry April 16/1978 s m 58.4 3.1+ Scale Cards/MOELP files Cranberry April 3/1977 s m 55.9 4.1+ Scale Cards/MOELP files Cranberry April 3/1977 s m 59.0 4.1+ Scale Cards/MOELP files Cranberry Oct. 30/1975 s f 63.5 4.1+ Scale Cards/MOELP files Cranberry Nov. 7/1974 s f 68.0 3.2+ Scale Cards/MOELP files Damdochax Sept. 6/1996 s m 73.66 Belford-data/MOELP files Damdochax Sept. 9/1996 s m 81.28 Belford-data/MOELP files Damdochax Sept. 11/1996 s u Belford-data/MOELP files Damdochax Sept. 15/1996 s f 71.12 Belford-data/MOELP files Damdochax Sept. 15/1996 s m 93.98 Belford-data/MOELP files Damdochax Sept. 20/1996 s f 71.12 Belford-data/MOELP files Damdochax Sept. 20/1996 s m 81.28 Belford-data/MOELP files Damdochax Sept. 20/1996 s m 99.06 Belford-data/MOELP files

50 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Damdochax Sept. 20/1996 s m 76.20 Belford-data/MOELP files Damdochax Sept. 20/1996 s m 76.20 Belford-data/MOELP files Damdochax Sept. 20/1996 s f 76.20 Belford-data/MOELP files Damdochax Sept. 20/1996 s m 86.36 Belford-data/MOELP files Damdochax Sept. 21/1996 s m 81.28 Belford-data/MOELP files Damdochax Sept. 24/1996 s f 76.20 Belford-data/MOELP files Damdochax Sept. 24/1996 s m 83.82 Belford-data/MOELP files Damdochax Sept. 24/1996 s f 66.04 Belford-data/MOELP files Damdochax Sept. 24/1996 s m 53.34 Belford-data/MOELP files Damdochax Sept. 24/1996 s f 76.20 Belford-data/MOELP files Damdochax Sept. 24/1996 s m 86.36 Belford-data/MOELP files Damdochax Sept. 24/1996 s m 81.28 Belford-data/MOELP files Damdochax Sept. 24/1996 s u Belford-data/MOELP files Damdochax Sept. 25/1996 s f 71.12 Belford-data/MOELP files Damdochax Sept. 27/1996 s m 93.98 Belford-data/MOELP files Damdochax Sept. 27/1996 s f 68.58 Belford-data/MOELP files Damdochax Oct. 5/1996 s m 66.04 Belford-data/MOELP files Damdochax Oct. 5/1996 s u Belford-data/MOELP files Damdochax Oct. 5/1996 s u Belford-data/MOELP files Damdochax Oct. 21/1996 s f 71.12 Belford-data/MOELP files Damdochax Oct. 23/1996 s f 66.04 Belford-data/MOELP files Damdochax Oct. 28/1996 s m 81.28 Belford-data/MOELP files Damdochax Oct. 15/1996 s m 73.66 Belford-data/MOELP files Damdochax Oct. 8/1996 s f 76.20 Belford-data/MOELP files Damdochax Oct. 6/1996 s f 81.28 Belford-data/MOELP files Damdochax Oct. 6/1996 s f 83.82 Belford-data/MOELP files Damdochax Oct. 23/1996 s f 73.66 Belford-data/MOELP files Damdochax Oct. 28/1996 s f 68.58 Belford-data/MOELP files Damdochax Oct. 28/1996 s f 78.74 Belford-data/MOELP files Damdochax May 4/1994 s m 82.0 field notes/blood sampling Damdochax May 4/1994 s m 62.0 field notes/blood sampling Damdochax May 4/1994 s f 73.0 field notes/blood sampling Damdochax May 4/1994 s f 73.0 field notes/blood sampling Damdochax May 4/1994 s f 81.0 field notes/blood sampling Damdochax May 4/1994 s f 73.0 field notes/blood sampling Damdochax May 4/1994 s f 70.0 field notes/blood sampling Damdochax May 10/1994 s f 83.0 field notes/blood sampling Damdochax July 26/1993 s f 67.0 2.2+ Alexander and Koski 1995 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 5.1+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 3.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 3.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s f 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.1+ Letter to Ken Belford July 24/1979 Damdochax May-79 s f 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s f 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s f 3.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979

51 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Damdochax May-79 s m 4.1S1+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m R.2+ Letter to Ken Belford July 24/1979 Damdochax May-79 s m 4.2+ Letter to Ken Belford July 24/1979 Damdochax Oct. 1/1979 r? m 38.1 Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 1/1979 s m 55.9 Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 1/1979 s f 43.2 Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 1/1979 s f 86.4 3.2S1+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 1/1979 s f 73.7 4.2+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 1/1979 s f 71.1 3.2+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 2/1979 s f 73.7 R.2+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 2/1979 s m 94.0 3.3+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 2/1979 s f 72.4 4.2+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 3/1979 s m 61.0 4.1+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 4/1979 s f 85.1 4.2+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 5/1979 s f 61.0 Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 6/1979 s f 73.7 R.2+ Memorandum/MOELP files Oct. 29/1979 Damdochax Oct. 6/1979 s f 83.8 R.2S1+ Memorandum/MOELP files Oct. 29/1979 Damdochax Dec.7/1979 s f 4.2S+ Scale Cards/MOELP files Damdochax Dec.7/1979 s f 73.7 4.2+ Scale Cards/MOELP files Gingolx area July 29/1993 s m 73 2.2+ Alexander and Koski, 1995 Sept. 14/1995 Ishkheenickh April 20/1994 s m 69.0 field notes/blood sampling Ishkheenickh April 20/1994 s f 86.0 field notes/blood sampling Ishkheenickh April 20/1994 s f 88.0 field notes/blood sampling Ishkheenickh April 20/1994 s f 86.0 field notes/blood sampling Ishkheenickh April 20/1994 s f 88.0 field notes/blood sampling Ishkheenickh April 20/1994 s f 86.0 field notes/blood sampling Ishkheenickh April 20/1994 s f 88.0 field notes/blood sampling Ishkheenickh May 7/1990 s f 81.0 STHD tagging record June 4/1990 Ishkheenickh May 7/1990 s f 81.0 STHD tagging record June 4/1990 Ishkheenickh May 7/1990 s f 74.0 STHD tagging record June 4/1990 Ishkheenickh May 7/1990 s f 64.0 STHD tagging record June 4/1990 Ishkheenickh May 7/1990 s f 64.0 STHD tagging record June 4/1990 Ishkheenickh May 7/1990 s f 71.0 STHD tagging record June 4/1990 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s f Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s m Memorandum/MOELP files June 5/1987 Ishkheenickh May 22/1987 s m Memorandum/MOELP files June 5/1987

52 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Ishkheenickh May 22/1987 s m Memorandum/MOELP files June 5/1987 Ishkheenickh April 15/1987 s m 91.4 Memorandum/MOELP files June 8/1987 Ishkheenickh April 15/1987 s m 81.3 Memorandum/MOELP files June 8/1987 April 15 steelhead Ishkheenickh April 15/1987 s m 68.6 Memorandum/MOELP files June 8/1987 No. Age Ishkheenickh April 15/1987 s f 86.4 Memorandum/MOELP files June 8/1987 1 3.2 Ishkheenickh April 15/1987 s f 71.1 Memorandum/MOELP files June 8/1987 1 3.3 Ishkheenickh April 15/1987 s f 83.8 Memorandum/MOELP files June 8/1987 4 4.3 Ishkheenickh April 15/1987 s f 86.4 Memorandum/MOELP files June 8/1987 1 R.2S1 Ishkheenickh April 15/1987 s f 75.0 Memorandum/MOELP files June 8/1987 1 3.2SS1 Ishkheenickh May 5/1985 s f ? R.3 Scale Cards/MOELP files Ishkheenickh May 5/1985 s f ? 3.2 Scale Cards/MOELP files Ishkheenickh May 5/1985 s f ? 3.3 Scale Cards/MOELP files Ishkheenickh May 5/1985 s f ? R.2 Scale Cards/MOELP files Ishkheenickh May 5/1985 s f ? 3.3 Scale Cards/MOELP files Ishkheenickh May 5/1985 s m ? 3.3 Scale Cards/MOELP files Ishkheenickh May 5/1985 s f ? 3.3 Scale Cards/MOELP files Ishkheenickh May 5/1985 s m ? ? Scale Cards/MOELP files Ishkheenickh April 25/1982 s m 66.0 3.1S1 Scale Cards/MOELP files Ishkheenickh May 13/1978 s f 4.1S1 letter to Paul Foote July 19/1978 Ishkheenickh May 13/1978 s f 4.1S1 Scale Cards/MOELP files Ishkheenickh May 13/1978 s m 69.0 4.2 Scale Cards/MOELP files Ishkheenickh May 6/1978 s m 67.3 4.2 Scale Cards/MOELP files Ishkheenickh May 6/1978 s f 83.8 3.1S1 Scale Cards/MOELP files Kiteen Dec. 2/1984 s f ? 3.2+ Scale Cards/MOELP files Kiteen Aug. 24/1982 s f ? ? Scale Cards/MOELP files Kiteen April 3/1977 s m 81.0 3.2+ Scale Cards/MOELP files Kwinageese Oct. 19/1995 s f 86.4 raw data/DNA sampling Kwinageese Oct. 19/1995 s m 71.1 raw data/DNA sampling Kwinageese Oct. 19/1995 s f 82.6 raw data/DNA sampling Kwinageese Oct. 19/1995 s m 61.0 raw data/DNA sampling Kwinageese Oct. 19/1995 s m 78.0 raw data/DNA sampling Kwinageese Oct. 19/1995 s f 78.0 raw data/DNA sampling Kwinageese Oct. 19/1995 s m 84.0 raw data/DNA sampling Kwinageese Oct. 19/1995 s f 81.0 raw data/DNA sampling Kwinageese Oct. 19/1995 s f 84.0 raw data/DNA sampling Kwinageese Oct. 19/1995 s f 65.0 raw data/DNA sampling Kwinageese Oct. 19/1995 s m 85.0 raw data/DNA sampling Kwinageese Aug. 9/1993 s m 69.0 4.2+ Alexander and Koski, 1995 Sept. 14/1995 Kwinageese Oct. 12/1982 s f 76.2 4.2+ Kwin summary 1982 fall 1982 Kwinageese Oct. 13/1982 s f 71.1 3.2+ Kwin summary 1982 fall 1982 Kwinageese Oct. 13/1982 s m 61.0 3.1+ Kwin summary 1982 fall 1982 Kwinageese Oct. 13/1982 r m 39.4 Kwin summary 1982 fall 1982 Kwinageese Oct. 13/1982 s m 81.3 3.2+ Kwin summary 1982 fall 1982 Kwinageese Oct. 13/1982 s m 71.1 4.1+ Kwin summary 1982 fall 1982 Kwinageese Oct. 16/1981 s m 83.8 3.1S1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s m 76.2 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s m 88.9 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s m 76.2 4.1S1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s m 50.8 3.1+ Schultze 1981-SK-37 1981

53 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Kwinageese Oct. 16/1981 s f 76.2 3.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s m 58.4 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s m 63.5 4.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s m 58.4 4.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s f 71.1 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s f 71.1 3.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s f 76.2 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s f 55.9 4.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s f 76.2 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s f 61.0 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 16/1981 s f 76.2 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 96.5 4.3+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 55.9 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 71.1 3.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 83.8 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 55.9 4.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 55.9 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 73.7 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 73.7 3.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 76.2 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 86.4 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 71.1 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 58.4 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 66.0 4.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 76.2 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 78.7 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 61.0 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 58.4 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 66.0 3.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 55.9 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 61.0 4.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 88.9 R.1S1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 61.0 4.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 81.3 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 83.8 R.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 94.0 3.3+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 55.9 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 81.3 3.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s f 76.2 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 61.0 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 17/1981 s m 61.0 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 18/1981 s m 58.4 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 18/1981 s f 73.7 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 18/1981 s m 61.0 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 18/1981 s f 53.3 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 18/1981 s m 62.2 3.1+ Schultze 1981-SK-37 1981 Kwinageese Oct. 18/1981 s f 73.7 4.2+ Schultze 1981-SK-37 1981 Kwinageese Oct. 18/1981 s m 61.0 4.1+ Schultze 1981-SK-37 1981 Meziadin Sept. 17/96 s f 84.0 2.2+ fishway/scale cards

54 Nass River steelhead life history characteristics

River Collection Species Sex Length Age Data Source Source Date s=STHD (cm) Date r=RBT Meziadin Sept. 18/96 s f 64.5 3.1+ fishway/scale cards Meziadin Sept. 20/1996 s f 63.0 2.1+ fishway/scale cards Meziadin Sept. 22/1996 s f 65.5 3.1+ fishway/scale cards Meziadin Sept. 22/1996 s f 62.0 3.1+ fishway/scale cards Meziadin Oct. 9/96 s m 65.0 3.1+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 s m 62.0 3.1+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 s m 64.0 3.1+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 s m 80.0 3.2+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 s f 71.0 4.2+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 s f 74.0 3.2+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 s m 58.0 3.1+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 10/96 s f 77.0 4.2+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 22/96 s m 89.0 3.2S1+ Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 22.5 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 21.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 37.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 33.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 40.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 30.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 21.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 21.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 27.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 33.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 9/96 r NA 45.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Oct. 22/96 r NA 29.0 Memo to file/DNA sampling Oct. 15/1996 Meziadin Aug. 3/1993 s f 73.0 4.2+ Alexander and Koski, 1995 Sept. 14/1995 Meziadin Aug. 5/1993 s f 80.0 2.2+ Alexander and Koski, 1995 Sept. 14/1995 Seaskinnish Aug. 28/1993 s m 75.0 R.2+ Alexander and Koski, 1995 Sept. 14/1995 Tseax Aug. 13/1993 s f 68.0 R.2+ Alexander and Koski, 1995 Sept. 14/1995 Tseax Aug. 14/1993 s m 63.0 3.2+ Alexander and Koski, 1995 Sept. 14/1995 Tseax April 16/1987 s f 83.82 Memo to file June 8/1987 April 16 steelhead Tseax April 16/1987 s f 77.47 Memo to file June 8/1987 No. age Tseax April 16/1987 s m 68.58 Memo to file June 8/1987 5 3.3 Tseax April 16/1987 s m 93.98 Memo to file June 8/1987 1 3.4 Tseax April 16/1987 s m 83.82 Memo to file June 8/1987 1 4.2+ Tseax April 16/1987 s m 82.55 Memo to file June 8/1987 1 4.3 Tseax April 16/1987 s m 93.98 Memo to file June 8/1987 1 4.4 Tseax April 16/1987 s m 83.83 4.2 Memo to file June 8/1987 1 R.1S1 Tseax April 30/1978 s m 73.66 4.2+ Letter to Petrini July 19/1977 Tseax June 1/1975 s f 4.2 Scale Cards/MOELP files Tseax June 1/1975 s f 3.2 Scale Cards/MOELP files Tseax June 1/1975 s f 62.0 3.1S1 Scale Cards/MOELP files Tseax June 1/1975 s f 3.2+ Scale Cards/MOELP files Tseax April 30/1981 s m 73.7 4.2 Scale Cards/MOELP files Zolzap Aug. 16/1993 s f 77.0 4.3+ Alexander and Koski, 1995 Sept. 14/1995

55 Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 233 Outliers .053 526

.039 394

.026 263

.013 131

.000 0

0.00 2.50 5.00 7.50 10.00 Certainty is 40.35% from -Infinity to 1.00 Steelhead B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 344 Outliers .041 413

.031 309

.021 206

.010 103

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 1,468 Outliers .109 1093

.082 819

.055 546

.027 273

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

56 Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 236 Outliers .055 550

.041 412

.028 275

.014 137

.000 0

0.00 2.75 5.50 8.25 11.00 Certainty is 36.61% from -Infinity to 1.00 B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 182 Outliers .056 558

.042 418

.028 279

.014 139

.000 0

-5.00 -3.50 -2.00 -0.50 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 1,354 Outliers .127 1266

.095 949

.063 633

.032 316

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

57 Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 193 Outliers .058 580

.044 435

.029 290

.015 145

.000 0

0.00 4.38 8.75 13.13 17.50 Certainty is 25.80% from -Infinity to 1.00 B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 177 Outliers .056 558

.042 418

.028 279

.014 139

.000 0

-3.50 -2.38 -1.25 -0.13 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 831 Outliers .206 2055

.154

.103

.051 513

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

58 Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 217 Outliers .050 501

.038 375

.025 250

.013 125

.000 0

0.00 2.75 5.50 8.25 11.00 Certainty is 35.12% from -Infinity to 1.00 B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 186 Outliers .055 554

.042 415

.028 277

.014 138

.000 0

-4.50 -3.13 -1.75 -0.38 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 1,156 Outliers .133 1330

.100 997

.067 665

.033 332

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

59 Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 206 Outliers .055 550

.041 412

.028 275

.014 137

.000 0

0.00 4.38 8.75 13.13 17.50 Certainty is 21.42% from -Infinity to 1.00 B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 166 Outliers .051 512

.038 384

.026 256

.013 128

.000 0

-2.50 -1.63 -0.75 0.13 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 893 Outliers .166 1657

.124

.083 828

.041 414

.000 0

-2.00 -1.25 -0.50 0.25 1.00

60 Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 181 Outliers .055 553

.041 414

.028 276

.014 138

.000 0

0.00 3.75 7.50 11.25 15.00 Certainty is 28.05% from -Infinity to 1.00 B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 239 Outliers .049 487

.037 365

.024 243

.012 121

.000 0

-3.00 -2.00 -1.00 0.00 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 836 Outliers .181 1805

.135

.090 902

.045 451

.000 0

-4.00 -2.75 -1.50 -0.25 1.00

61 Nass River steelhead life history characteristics

A. Forecast: Recruits Per Spawner 10,000 Trials Frequency Chart 210 Outliers .054 539

.040 404

.027 269

.013 134

.000 0

0.00 3.13 6.25 9.38 12.50 Certainty is 33.50% from -Infinity to 1.00 B. Forecast: Allowable Harvest Rate 10,000 Trials Frequency Chart 110 Outliers .071 713

.053 534

.036 356

.018 178

.000 0

-6.00 -4.25 -2.50 -0.75 1.00

C. Forecast: Beverton-Holt's A Value 10,000 Trials Frequency Chart 1,163 Outliers .146 1460

.110

.073 730

.037 365

.000 0

-4.00 -2.75 -1.50 -0.25 1.00